Horseradish Cheddar Cheesy Cauliflower Gratin
This easy, cheesy cauliflower gratin is a lightened-up version of a classic comfort food side dish! Creamy mashed cauliflower is covered in melty cheddar with a hint of horseradish and baked until golden. This flavorful casserole can be prepared ahead for a busy weeknight or even a holiday meal.
My cauliflower au gratin, inspired by sweet potato gratin, is keto-friendly! You might also love my fully-loaded cauliflower mashed potatoes with bacon and cheddar, and this cheesy cauliflower casserole.
Today’s cauliflower gratin is a delicious casserole inspired by classic French potatoes au gratin. Similar to scalloped potatoes, any recipe au gratin consists of vegetables covered with cream sauce and baked. The main difference is that while cheese is optional in scalloped potatoes recipes, it’s a MUST in cauliflower au gratin. You’re going to love making this cheesy cauliflower side dish for the holidays and beyond, I just know it!
Why Cheesy Cauliflower Gratin Belongs on Your Holiday Menu
- Only 4 ingredients. Plus a handful of basic seasonings. That’s all you need to make it!
- Fluffy, creamy, and golden-baked. This casserole-style side dish is loaded with sharp Cabot Horseradish Cheddar (my favorite!), with Greek yogurt and an egg to make it fluffy and structured.
- A classic, made lighter. My mashed cauliflower gratin tastes different from mashed potatoes, but this low-carb side dish is rich, flavorful, and just as tasty in its own right.
- Any occasion. This cauliflower gratin recipe is easy enough to make for weeknight dinners and special enough for a holiday meal. I love having this casserole as a lighter option on our Christmas and Thanksgiving menus!
Gather These Ingredients
Scroll to the printable recipe card below the post for the full ingredients list, amounts, and recipe details.
- Cauliflower – You’ll need fresh florets from one head of cauliflower. Look for cauliflower with tight, firm curds that are clean and white without yellowing or blemishes. There’s no need to cut the cauliflower florets to any particular size, since you’ll be steaming and puréeing them.
- Egg – An egg helps bind the mashed cauliflower, giving it a thicker and fluffier texture.
- Plain Greek yogurt – Keeps the casserole creamy and fluffy without thinning it out. Sour cream is a good substitute if you need one.
- Horseradish Cheddar Cheese – I use horseradish-flavored sharp cheddar from Cabot Cheese. It adds so much flavor to the gratin! If you can’t find it or prefer a milder flavor, plain sharp cheddar cheese works just fine, too.
- Seasoning – Salt and pepper, with optional paprika on top to give the dish a little color.
How to Make Cauliflower Gratin
This technically isn’t a traditional cauliflower au gratin, since we’re mashing the cauliflower rather than leaving the florets whole or sliced. But, creative liberties never tasted so good! Here’s what to expect while preparing this recipe.
- Steam the cauliflower. First, steam the cauliflower in a steamer basket set over a pot of water until it’s very tender.
- Prepare the mash. Next, transfer the steamed cauliflower to a blender or food processor. Add the egg, yogurt, cheese, salt, and pepper. Pulse and purée until it is smooth.
- Assemble in a baking dish. Now, spread the mashed cauliflower evenly into a casserole dish. Top the mash with more shredded horseradish cheddar cheese. Sprinkle the casserole with paprika, if you like, for color and a hint of smokiness.
- Bake and serve. Bake this cauliflower gratin at 400°F for 25 to 20 minutes, until it’s hot and golden-brown on top. Baking it gives it that fluffy texture, just like mashed potatoes!
Recipe Tips and Variations
- Get rid of excess moisture. After you steam the cauliflower, take it out of the pot so some of the steam can evaporate and get rid of some of the liquid on the cauliflower.
- Choose your consistency. If you puree it in a high-powered blender, you will get a smooth and silky whipped cauliflower. A food processor makes them more like a thicker cauliflower mashed potatoes recipe.
- Make it fancy. If you are having a dinner party, you can put it into individual ramekins, as I did with this whipped cauliflower. Just adjust your baking time a bit to account for the smaller size.
Can I Make This Dish in Advance?
Yes. You can prepare all or part of this cauliflower gratin recipe ahead of time. This makes it ideal for busy weeknights OR holiday meals when I’m preparing lots of dishes! There are a few options:
- Pre-cook the cauliflower. Steam the cauliflower, then let it cool down and dry off. Then you just have to puree and bake when it’s time to serve.
- Prepare but don’t bake. Get the entire mashed cauliflower casserole prepared and refrigerate it unbaked. You’ll want to take it out of the refrigerator to warm up a bit or give it a little extra time in the oven to get hot all the way through.
- Bake and reheat. Bake it off completely, then reheat it in the oven to get the cheese extra toasty.
Storing and Reheating Leftovers
- Refrigerate. Whether you’ve made the cauliflower casserole in advance or just have leftovers, you can wrap it or cover it tightly and refrigerate it for 3 or 4 days. Do not freeze this casserole. Freezing and thawing make the cauliflower grainy and watery.
- Reheat. Then you can reheat it by microwaving all or a portion of it, or put it back in the oven at 350°F to 400°F for about 20 minutes until it is hot all the way through.
Serving Suggestions
I make this cauliflower au gratin for so many meals. It’s so quick that I can make it for weeknights to serve with cube steaks or an air fryer rotisserie chicken, but the flavor is a perfect match for holiday dinners. Pair this cauliflower side with glazed ham or brisket on Easter, prime rib at Christmas, or a Thanksgiving turkey with sides like cranberry sauce and stuffing. Don’t skip a slice of pumpkin pie for dessert!
I love to use my Blendtec. It is a high-powered blender that gives you the smoothies and creamiest mashed cauliflower, smoothies, soups, and more.
I am a Blendtec ambassador, and should you make any purchases through my Blendtec Store link, I will receive a small commission, but that also means you can use the code CUPCAKESANDKALECHIPS to receive 20% off.
Horseradish Cheddar Mashed Cauliflower Casserole
Ingredients
- 1 head cauliflower
- 1/4 cup plain Greek yogurt
- 1 egg
- 1 cup shredded Cabot Horseradish Cheddar Cheese , divided (about 4 oz.)
- 1 teaspoon kosher salt
- 1/8 teaspoon freshly ground black pepper
- paprika optional
Instructions
- Preheat your oven to 400°F, and lightly coat a 2 quart casserole dish with oil or cooking spray.
- Cut the cauliflower into large florets, discarding the tough stem, and steam over boiling water until very tender.
- Drain thoroughly, and allow to cool slightly so that some of the excess moisture evaporates.
- Place the cauliflower, Greek yogurt, egg, 3/4 cups of the cheese, salt, and pepper into a blender or food processor, and process until smooth.
- Transfer the cauliflower to the prepared dish and sprinkle with remaining cheese, and paprika, if desired.
- Bake for 25-30 minutes, or until heated through and browned on top.
Notes
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I have to say this is pretty darn good! I bought a horseradish cheese the other day bc it sounded so interesting, but wasn’t sure what to do with it. Yancey cheese suggested a casserole on their site, but I didn’t see a recipe. Anyways I found this and unfortunately forgot to get the greek yogurt so I used sour cream instead. Still delicious and amazing!
Horseradish cheddar is my very favorite and this recipe puts it to its best possible use. I love that you used Greek yogurt, too!
I love the horseradish cheddar too! I am thinking of a grilled cheese to make with it too!
I’m okay with mashed potatoes, but I’ll take this over them any day!