French Onion Stuffed Meatballs

4.7 from 13 votes
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Stuffed with caramelized onions and mozzarella, these French Onion Meatballs are a hearty meal inspired by the classic au gratin soup recipe. Homemade meatballs are covered with more cheese and broiled until golden brown and bubbly, for a comfort food dinner the entire family will enjoy!

French Onion Mozzarella-Stuffed Meatballs

As a kid of divorced parents, there were a handful of meals that my dad would make whenever I visited. They were always a little indulgent and catered to my childhood favorites: hot dogs and campfire potatoes around the fire pit in the summer, and in the winter, grilled cheese and French onion soup au gratin. 

I eagerly awaited those crocks of soup so that I could scoop up a perfect bite of savory, cheesy deliciousness. Fast forward, and this meatball recipe translates that childhood delight into meatball form!

This time around, mozzarella stuffed meatballs are browned and simmered in a rich sauce loaded with caramelized onions, filled with familiar flavors. The result is hearty comfort food that satisfies even the biggest appetites (trust me, I live with three of them!).

Close up of a French onion meatball scooped up with a wooden spoon.

Why is it Called a French Onion?

French Onion Soup is a classic soup recipe that originates in France, made with caramelized onions simmered in beef broth, topped with toast, and melted (often Gruyere) cheese. My dad’s version uses mozzarella, which inspired this meatball recipe! 

While most mozzarella stuffed meatballs are simmered in tomato sauce, these are smothered in a simple, rich sauce made of beef stock and red wine reminiscent of French onion soup. The meatballs are then baked until the cheese inside becomes a pocket of melty deliciousness. 

Of course, you can’t forget the au gratin. The entire pan gets covered in more mozzarella and placed under the broiler to get that perfectly browned cap of toasty cheese.

A mozzarella stuffed meatball cut in half to reveal the cheesy center.

What You’ll Need

I love these homemade meatballs because they’re effortlessly delicious. Like French onion soup, this recipe packs a ton of flavor all while using humble, easy-to-come-by ingredients. Here they are:

  • Onions: I prefer to use a sweeter yellow onion, such as a Vidalia onion. You can use your favorite, but this may lead to a stronger flavor.
  • Herbs: Fresh or dried thyme pairs wonderfully with the onions, plus fresh parsley for the meatball mixture.
  • Beef Broth: You’ll use beef broth when caramelizing the onions as well as in the sauce that the meatballs will simmer in.
  • Red Wine: Pinot Noir, or any red of choice. If you prefer to cook without alcohol, substitute wine with more beef broth.
  • Ground Beef: Or your preferred ground meat. I aim for 80-90% lean, regular ground beef when making these meatballs since it holds its shape and has a good amount of flavor.
  • Bread Crumbs: For a gluten free option, substitute gluten free bread crumbs or leave them out altogether. Another quick hack is to use gluten free oats that you’ve pulsed a few times in your blender.
  • Cheese: I use mozzarella because this is how my dad always made French Onion Soup. Feel free to substitute the more traditional Gruyere or even Swiss or Cheddar!
  • Egg: A binding agent to hold the meatballs in shape.
  • Olive Oil: Or another neutral oil for sauteing and browning.
  • Cornstarch: To thicken the sauce.
  • Salt & Pepper

How to Make French Onion Stuffed Meatballs

A note before getting started: You’ll need a nice, large skillet that is safe to put in the oven and under the broiler. I’ve included alternatives in my tips below! Other than that, everything you’ll need is pretty basic, such as measuring cups and spoons and a bowl. 

Once you have this plus your ingredients at the ready, here’s how to make the most amazing French onion meatballs:

Caramelize the Onions: Begin by sauteing the onions in olive oil until they’re golden and caramelized. Add the thyme, wine, and beef broth, and reduce until very little liquid remains. 

Make the Meatballs: Combine the raw meatball ingredients in a bowl. I use my hands to really work everything together! Next, divide the mixture into even-sized balls.

Stuff the Meatballs: Flatten each of the meatballs and place a small amount of the onions and a cube of cheese in the middle. Wrap the meat around the filling and form it into a ball, sealing as best as you can. Repeat with the remaining meat, onions, and cheese cubes.

Brown & Bake: Brown the meatballs in a skillet. Whisk together the sauce ingredients and pour this over the meatballs, then transfer the skillet to a preheated oven to bake. About half way through, sprinkle the shredded cheese over top of the meatballs as they continue to cook.

Broil: Once the meatballs are cooked through and the cheese is melted, switch on the broiler until the cheese is browned and bubbly.

French onion meatballs topped with broiled cheese in a skillet.

Variation Ideas

  • Make Chicken or Turkey Stuffed Meatballs: Trade out the ground beef for leaner meats like ground chicken or ground turkey (ground pork is also an option). 
  • Stuff Them With Different Cheeses: Instead of mozzarella, try stuffing your French onion meatballs with other cheese varieties like cheddar, ricotta, Monterey Jack, or even Gruyere cheese.
  • Switch Up the Sauce: You can bake these meatballs in other savory sauces, like tomato sauce, Vodka Sauce, or a homemade Red Gravy.
  • Add In Extras: In addition to caramelized onions and thyme, you can add other ingredients to the meatball filling like mushroom duxelles, as well as different herbs like fresh chopped basil and rosemary. 
French onion meatballs in gravy on a plate.

Tips for Success

  • Don’t Rush: It’s important to caramelize the onions slowly, so that they develop the deep caramelized color and flavor without burning. Be sure to stir frequently and reduce the heat if necessary.
  • Use the Right Wine: Most red wines will work well for this recipe. It doesn’t need to be an expensive bottle, but I would recommend using a wine you would drink (versus cooking wine).
  • Use Oven-Safe Equipment (or an Alternative): I like using my 10-inch cast iron skillet as it browns the meatballs nicely and it’s oven (and broiler) safe. If you do not have an oven-safe skillet, transfer the meatballs to a casserole dish before adding the sauce and baking them in the oven.

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Can I Make These in Advance?

One of the best parts about this recipe? If you have the time, you can make loads of these delicious onion and mozzarella stuffed meatballs. They’re the perfect recipe to prepare in advance, for later baking or freezing. You can even freeze the meatballs raw (just as long as you’re working with meat that was fresh and not frozen to begin with). See my tips below for how to store and freeze them!

French onion meatballs in gravy on a plate.

Make it a Meal

Savory, saucy French onion meatballs are wonderful to serve over egg noodles, rice, mashed potatoes, or even spaghetti squash for a low-carb option. They also pair perfectly with these easy side dishes:

French onion meatballs served next to a glass of red wine.

Storing and Reheating Leftovers

Store leftover meatballs airtight in the fridge for up to 3-4 days. Gently reheat the meatballs in the oven or microwave, or even in a skillet on the stove. You may want to give them a fresh sprinkle with cheese once they’re warm to revive the topping a bit.

Do Stuffed Meatballs Freeze Well?

These stuffed meatballs freeze really well! Place the cooked or uncooked meatballs in a single layer on a baking sheet to pre-freeze. Once they’re solid, transfer them to freezer bags to keep frozen for up to 3-4 months. Let the meatballs thaw in the fridge before browning and/or baking them in the sauce.

A French onion and mozzarella stuffed meatball on a fork.

More Homemade Meatballs to Try

French onion meatballs topped with broiled cheese in a skillet.
4.7 from 13 votes

French Onion Meatballs

Stuffed with caramelized onions and mozzarella, these French Onion Meatballs are a hearty meal inspired by the classic au gratin soup recipe. A comfort food dinner the entire family will enjoy!
Prep: 20 mins
Cook: 1 hr 10 mins
Total: 1 hr 30 mins

Ingredients

For the onions

  • 1 Tablespoon olive oil
  • 2 large onions, halved and thinly sliced
  • 1/2 Tablespoon fresh thyme or 1/2 teaspoon dried thyme
  • 1 teaspoon salt
  • 1/2 teaspoon pepper
  • 1/4 cup beef broth
  • 1/4 cup red wine (I used Pinot Noir, but your favorite red wine will work, or substitute beef broth)

For the meatballs:

  • 1 1/2 lbs ground beef
  • 1/4 cup bread crumbs or ground oats, gluten free, if needed
  • 1 Tablespoon minced fresh parsley
  • 3/4 teaspoon pepper
  • 1 teaspoon kosher salt
  • 1 large egg
  • 8 oz mozzarella cheese, cut about 1-2 oz. into sixteen approximately half-inch cubes to stuff the meatballs, then shred the rest
  • 1/2 Tablespoon olive oil
  • Fresh chopped parsley for garnish, optional

For the sauce:

  • 1 3/4 cup beef broth
  • 1/4 cup red wine (I used Pinot Noir, but your favorite red wine will work, or substitute with aditional beef broth)
  • 2 Tablespoons cornstarch
  • salt & pepper to taste

Instructions

For the onions:

  • Heat oil in a skillet over medium, add onions, salt & pepper, cook 15-20 minutes, stirring frequently or until caramelized.
  • Add thyme, sauté for minute or two, then add the wine and beef broth.
  • Reduce until very little liquid remains.
  • Set aside.

For the meatballs:

  • Combine all ingredients except the cheese in a large bowl, and gently combine with your hands.
  • Divide the meat mixture into sixteen equal pieces.
  • Take one piece of the meat mixture and flatten slightly into a patty. Place about a half tablespoon of the onions and one cube of cheese in the center of the patty and wrap the meatball around the onions and cheese, sealing as best you can. Repeat with the remaining meat, onions, and cheese cubes.
  • Preheat your oven to 375°F.
  • Heat the oil in a skillet over medium high heat. Add the meatballs and brown on all sides.
  • Whisk together the sauce ingredients and pour over the meatballs. Place in the oven and bake for 15-20 minutes. If you are not using an oven-safe skillet, transfer to a casserole dish before pouring over the sauce.
  • Sprinkle the shredded cheese over the meatballs and return to the oven for another 15-20 minutes, or until cooked through, then place under the broiler for 2-3 minutes, or until the cheese is browned and bubbly.
  • Garnish with fresh parsley, if desired.
Nutrition Facts
French Onion Meatballs
Amount Per Serving (3 meatballs)
Calories 452 Calories from Fat 198
% Daily Value*
Fat 22g34%
Saturated Fat 10g50%
Cholesterol 152mg51%
Sodium 1717mg72%
Potassium 668mg19%
Carbohydrates 13g4%
Fiber 1g4%
Sugar 2g2%
Protein 42g84%
Vitamin A 455IU9%
Vitamin C 5.4mg7%
Calcium 274mg27%
Iron 4.4mg24%
* Percent Daily Values are based on a 2000 calorie diet.
139 Comments
  1. Carolyn T

    5 stars
    Made these last night. WOW! Vivid flavors, lots of umami. I happened to have some sweet onions to use for this, although they take longer to caramelize – probably more like 35 minutes. Actually I forgot to put the onions IN the meatballs, so I put the onions on the bottom of a casserole dish, meatballs, sauce, then the cheese. Perfection. It will definitely make another appearance on my dinner table.

  2. misty

    even more ‘manly man’ with venison, lol. I enjoy your writing!! 🙂
    try it.
    I guarantee it will taste good. man, elk is good! what was bad about that?? (except it was too much like bambi for a teenage girl? IDK. 🙂 …..I NEVER think of bambi when I’m eating venison, or rudolph! LoL . We’ve romanticized deer too much!
    one thing I do with venison meatloaf and probably balls, too is to drench it in 1 cup of milk and use 1 cup of crackers, oatmeal or bread crumbs. Seriously, you CANNOT tell it is venison. It is leaner, healthier and delicious with bbq sauce.
    (And my venison is free, so ……that makes it taste better, too) . 🙂
    Thanks again, Love your page

    1. Brianne Cupcakes & Kale Chips

      I’m so glad you and your family enjoy the meatballs, Rachelle. Thank you for your comment and for rating the recipe!

  3. Rebecca

    Do you think it would be just as good if I made it Ahead of time? That way I could just put it in the oven when my guests arrive

  4. 5 stars
    I think you should go visit Dad and make it for him. Tell him it is a tribute to him and he will be so touched. I have to say this is fantastic. The meatball idea is pure genius. Just the way us guys need and like it. Great tip on how to flatten the meat balls and add the cheese cube inside. Love it.

  5. Shelby

    These look really good and I plan on trying them. I’m glad that you have the nutritional value on the recipe. What is the serving size though? I count carbs for my diabetes and I try to stay as close to accurate calculations as possible, on the nutritional values. Thank you for sharing.

    1. Brianne Cupcakes & Kale Chips

      Hi Shelby! I’ve updated the nutritional information for the recipe. One serving is 3 meatballs.

  6. Lauren L

    We just ate these and all I can say is WOW!!!! Delicious! Made exactally except no breadcrumbs in meatballs cause we are low carb… Oh my, absolutally wonderful. Thank you so much…..

  7. LeAnn Troutman

    Made this tonight…….family loved it!!!
    Very flavorful. ….my teenage son is in the fridge now eating the leftovers! Pure Yumminess!!

  8. Natasha

    5 stars
    I made these a couple of weeks ago and they were beyond AMAZING! They definitely fell into my top 5 “Best Things I’ve Ever Made” list!! I’m probably going to make them again tonight. I made them exactly like your recipe and they were so incredible. My best friend and fiance rave about them. Thanks so much for posting this!!!

    1. I am wondering if I missed the mention of the size of the skillet somewhere, it looks very large, I do have a 8 inch, 10 inch and 14 inch cast iron skillet. Thanx for all your wonderful recipes.

  9. Carla

    Have these in the oven right now… Upon another review of the recipe, I realize I have goofed… I made 8 extra large meatballs. When reading the directions to flatten a meatball, I assumed it needed topped with another one. Fingers crossed it still turns out okay.

  10. Aly

    Couple of ideas for you: I know you were supported by a wine company but I think better onion soup has either sherry or brandy in it. I make an easy onion soup with caramelized onions, 1 can chicken broth or homemade : (low sodium swanson’s) i can beef broth (swanson’s also) and 1 can beef consomme (campbells is fine) also use gruyere and or emmenthaler cheeses to top, the mini mozzarella pearls would be great for stuffing. Also a combination of ground pork and ground beef would be a moister meatball. I learned a little trick: beat the pork well with bread crumbs soaked in milk and the seasonings to a smooth past. then gently combine the beef. Pork does not toughen like the beef and will get better as it is beaten. The panade or milk bread mixture helps keep it moist. Try this and tell me what you think. Aly

  11. Katie B.

    4 stars
    I made these tonight and they were a hit! I served them over mashed potatoes and topped off with sautéed portobello mushrooms. Yum!

  12. Brianne – these meatballs knocked my SOCKS OFF!!! They were so delicious and perfect! I served them over rice and we loved, loved, loved them!! Thank you so much! I hope you won’t mind if I feature them on my blog (with my own pictures and link backs 🙂
    All the best, Heather

  13. Cathy O

    5 stars
    I prepared these last night, so all my husband has to do is bake them in the oven. I can’t wait to try them. I had a lot of onion left over, so I spread them on the bottom of the casserole dish. I will let you know how they taste!

  14. Nadine

    I just finished my meal. ..oh my oh my! Incredible . I made a few changes and want to share with you . I couldn’t have a dinner like this without garlic so I added minced garlic to the meatballs and sliced garlic to the sauce. I don’t like the texture eggs give to meatballs so I soaked the crumbs in beef broth. I stuffed the meat with aged cheddar and topped them with Swiss cheese, parsley and chives from my garden. Oh, since I am not a huge fan of thyme, I used herb d’ Provence. This is a keeper….thank you so much for this favorite . I hope I haven’t offended you with all the changes!
    Nadine

      1. Nadine

        I have been trying to get on your email list but for some reason I can’t . Can you add me? diny@ live .ca
        Thanks again, leftovers tomorrow . And , I have shared with the neighbours.
        N

          1. Nadine

            Yes, I am getting your emails . I am making this recipe again tonight…it’s my new favorite ! Thanks again.

  15. Nadine

    Hi, this looks amazing. I am making it this evening. I have a question, for the onion recipe there are two different measurements for thyme. Can you explain this to me please. Maybe I missed something as no one else commented on this.
    Thanks so much,
    N

  16. elaine laskowski

    This was way to much trouble for the mediocre result. I thought it would be fantastic, I was so disappointed in this recipe.

    1. Nadine

      One less step I did was not to use the onions in the stuffing. It would have been too tedious for me and I really wanted the onions in the sauce. I did it in steps, not all at once. Hope this helps.

  17. Holly

    Stumbled across this while browsing Pinterest and made it last night. After one bite, I knew I had to come here and tell you how wonderful it is!! Both the husband and I loved it so incredibly much. I served it with some balsamic roasted tomatoes and crutsy bread for dipping. Super huge hit!!

  18. DEBI G

    I MADE THESE LAST NIGHT AND THEY WERE GREAT, THE FLAVORS WERE TRUE TO THE ORIGINAL SOUP. I WOULD SERVE THESE ON A SLICE OF TOASTED BREAD AND POUR THE SAUSE OVER IT AND ENJOY.

    I WAS ABLE TO PICK THE HERBS FRESH FROM THE GARDEN.

  19. I still remember the first time I tried French onion soup was at a French restaurant with my dad. These tasty meatballs would be a delicious dish to relive that fun memory. They look wonderful!!

  20. Lori Hart

    OMG – These look incredible! Something hubby and I would love. I found you over at the Cast Party Wednesday link party. I host Tickle My Tastebuds Tuesday and would love it if you linked up this recipe. I’m sure our party goers would love it as much as I do. Here is the link http://bit.ly/1l4cu0j. Have a wonderful day!!

  21. I love all your food memories with your dad, healthy or not they stay with you. Also what kid doesn’t have fond memories of eating onion soup? It’s the one that comes with the cheese! I love these meatballs. I could probably put down that tray.

  22. Lynn

    We had a french onion chicken breast dish at a friend’s house that was amazing but I never found a recipe. So glad to find this one! Can’t wait to make it for Father’s Day!

  23. Deborah

    This sounds delish! I cannot wait to try it! I will be using Swiss cheese though instead of the mozzerella since that is the traditional cheese used in French Onion Soup. Thanks for the recipe : )

  24. Two thumbs up to your father’s version of French Onion Soup! And, oh my goodness, your meatballs with mozzarella tucked inside swimming in the Gallo wine infused sauce must be heavenly! Certainly your pictures give that impression. Thank you for sharing this marvelous recipe!

      1. Due to health reasons, the small amount that remains may be a concern for some people. I had a friend in college who had a heart transplant, and it can be a big deal with the medications and all. It will still be a fabulous dish, even without the wine.

  25. cindyzs

    your dishes and photos ALWAYS make me so hungry it’s not funny! i think i could eat the whole thing, lol 🙂 tfs

  26. Katie

    Loving this dish! I mean…the cheese. There is something so wonderful about bubbly, golden brown, toasty cheese.

    I don’t know that my dad really has a “specialty” when it comes to cooking. He’s always been the grill master around the house…I guess that counts!

  27. Just put the whole skillet down in front of me and let me eat my way though it. Then I’ll take a big loaf of bread and sop up every single drop of that sauce. Awesome.

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