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French Onion Cheese Stuffed Meatballs has everything you love about the classic French Onion Soup Au Gratin recipe in a hearty meal to satisfy any appetite. Mozzarella stuffed meatballs are browned and simmered in a rich sauce loaded with caramelized onions. Then, of course, they are topped with more ooey gooey cheese! And you can easily make them gluten free with no breadcrumbs and a simple swap!
Originally published on June 8, 2014. Updated on September 13, 2017, and January 13, 2019, with video, process shots, and additional details and information.
My parents got divorced when I was five years old. Strangely, most of my food memories are of the snacks and treats that I only had when I was with dad. Cheese Doodles and Chips Ahoy and Chocolate Pudding Pie and S’Mores. I think many little kids of divorced parents get spoiled a bit when they go visit the parent they don’t live with, and I was no exception.
But I know my dad fed me meals, too. The funny thing is, only two stand out in my mind. One is hot dogs, “Campfire” Potatoes, and corn on the cob when we spent summer evenings around the fire pit in his backyard. The other was our cold-weather favorite – grilled cheese and French Onion Soup au Gratin. Because, you know, can you really have too much bread and cheese in one meal? I think not.
What is French Onion Soup?
French Onion Soup is a classic soup recipe that originated in France, where it is known as soupe à l’oignon. It consists of onions that are slowly caramelized and then simmered in broth or stock, typically a meat stock like beef. To turn it into the ultimate French Onion Soup Au Gratin, the soup was ladled into a bowl and topped with toasted bread or croutons and cheese, most often Gruyere cheese. It was then broiled until the cheese was melty, golden brown, and bubbly.
My dad might have had a simpler way to make it, but it was still incredible.
French Onion Soup (albeit from a can) was gently simmered until hot and poured into crocks. He topped it toast and plenty of mozzarella cheese (not traditional, but that’s how Dad made it), and put under the broiler until it bubbled and browned.
I eagerly awaited those crocks being removed from the oven and placed on the table so that I could pierce my spoon through the gooey layers. I would scoop up a perfect bite with some of each component, drawing it towards my open mouth, thin strands of cheese slowly stretching their way from the bowl until I pursed my lips around the spoon and broke them off, sighing with delight as the aromas and flavors enveloped me in warmth and comfort and love.
Sadly I have a family that doesn’t love soup.
So taking those same flavors from my childhood favorite and turning it into a hearty, satisfying, comfort food dinner that could satisfy even the biggest appetites (trust me, I live with three of them) was really the only option. I might have a bad habit of eating just one more than I really should! They are that good.
Caramelized Onion Mozzarella Stuffed Meatballs Recipe
You’ll start by caramelizing onions with Pinot Noir (though any red wine would work), and stuffing the onions, along with a cube of mozzarella cheese, inside the meatballs. Then brown the meatballs in a skillet.
While most mozzarella stuffed meatballs are simmered in tomato sauce, these are smothered in a simple, rich sauce made of beef stock and more red wine. It is almost a gravy, but not quite so thick and heavy. The cheese stuffed meatballs are then baked in the oven until they were cooked through and the cheese became a pocket of melty deliciousness.
And of course, you can’t leave off the au Gratin, so the entire pan gets covered in more mozzarella and placed under the broiler to get that perfectly browned cap of toasty cheese.
What do you need to make French Onion Cheese Stuffed Meatballs?
For the caramelized onions:
- olive oil
- onions – thinly sliced. BRIANNE’S PRO TIP: I prefer to use a sweeter yellow onion, such as a Vidalia onion. You can use your favorite, but this will lead to a stronger flavor.
- fresh or dried thyme
- salt and pepper
- beef broth
- red wine – I used Pinot Noir, but any red wine will work. BRIANNE’S PRO TIP: It does not have to be an expensive bottle. However, I do recommend a wine you would drink versus cooking wine. If you prefer to cook without alcohol, you can substitute more beef broth.
For the meatballs:
- ground beef
- bread crumbs – for a GLUTEN FREE option, you can substitute gluten free bread crumbs, or use gluten free oats that you’ve pulsed a few times in your blender.
- fresh parsley
- salt and pepper
- mozzarella cheese – about 1-2 oz. of this will be cut into cubes to stuff in the meatballs. The remainder is shredded to put on top. BRIANNE’S PRO TIP: I use mozzarella because that is how my dad always made French Onion Soup. Feel free to substitute the more traditional Gruyere or even Swiss or Cheddar.
- olive oil – or any other neutral oil for browning the meatballs
For the sauce:
- beef broth
- red wine – I used Pinot Noir, but any red wine will work. As I mentioned earlier, it does not have to be an expensive bottle, but I do not recommend cooking wine. If you prefer to cook without alcohol, you can substitute more beef broth.
- salt and pepper
You’ll also need a nice, large skillet that is safe to put in the oven and under the broiler. I like using a 10-inch cast iron skillet as it helps with getting the meatballs nicely browned on the outside, and it is 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 in the oven.
Other than that, everything you’ll need is pretty basic, such as measuring cups and spoons and a bowl.
How to caramelize onions:
- Heat oil in a skillet over medium heat.
- Add sliced onions, salt, and pepper, cook slowly, about 15-20 minutes until golden and caramelized. BRIANNE’S PRO TIP: It is important to do this slowly so that you develop the deep caramelized color and flavor without burning the onions. Be sure to stir frequently and reduce the heat if necessary.
- Add thyme, wine, and beef broth, and reduce until very little liquid remains.
How to make cheese stuffed 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.
- Flatten one piece of meat, place a small amount of the onions and a cube of cheese in the middle. Wrap the meat around the filling and form into a ball, sealing as best as you can. Repeat with the remaining meat, onions, and cheese cubes.
- Brown the meatballs on all sides in a skillet over medium-high heat.
- Whisk together the sauce ingredients and pour over the meatballs. Transfer the skillet to the preheated oven.
- Bake at 375° for 15-20 minutes.
- Sprinkle the shredded cheese over the meatballs and bake 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 additional parsley, if desired.
Can you freeze stuffed meatballs?
Yes, you can freeze any leftovers. Before eating, just thaw slowly in the refrigerator, and gently reheat in the oven or microwave, or even in a skillet on the stove. The texture of the cheese topping might be affected slightly, so you could also make extra and freeze the cooked meatballs and sauce before topping with cheese.
What should I serve with stuffed meatballs?
You can spoon them over egg noodles, rice, mashed potatoes, or spaghetti squash. Or try some of these side dish recipes:
- Parmesan Balsamic Caramelized Onion Mashed Potatoes
- Horseradish Cheddar Mashed Cheesy Cauliflower Gratin
- Roasted Balsamic Mushrooms with Garlic and Rosemary
- Creamy Balsamic Healthy Salad Dressing over lettuce
- Light Creamed Spinach au Gratin
- Balsamic Roasted Vegetables
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Want more meatballs?
- Barbecue Baked Turkey Meatballs
- Grandma’s Polish Porcupine Meatballs
- General Tso’s Chicken Meatballs
- Pineapple Teriyaki Turkey Meatballs
If you like this, you’ll love these recipes:
- French Onion Cheese Stuffed Meatloaf
- French Onion Stuffed Burgers
- Lasagna Mozzarella Stuffed Meatloaf
- French Onion Salisbury Steak from Nutmeg Nanny
- French Onion Macaroni and Cheese from Dinners, Dishes, and Desserts
- Cheesy French Onion Chicken Sandwiches from Wonky Wonderful.
French Onion Cheese Stuffed Meatballs Recipe
Stuffed with caramelized onions and mozzarella, these French Onion Meatballs are a hearty meal inspired by the classic au gratin soup recipe. And for the best part, they are covered with even more cheese and broiled until golden brown and bubbly. It’s a comfort food dinner recipe the entire family will enjoy.
French Onion Soup au Gratin Stuffed Meatballs
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 , about 1-2 oz into sixteen approximately half-inch cubes, to stuff the meatballs, the remainder shredded
- 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
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.