Allow me to introduce you to this cheesy Cauliflower au Gratin, your new favorite easy low-carb recipe! Roasted cauliflower is coated in a sauce made with Gruyere and Parmesan cheese, then baked in the oven. Serve this vegetarian casserole for Thanksgiving, Christmas, or any holiday dinner when you want to impress!
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To say this Cauliflower au Gratin is out-of-this-world delicious would be the understatement of the year. Even my picky eaters in the family went back for seconds and thirds of this low-carb casserole!
(Something this Mashed Cauliflower and Whole Roasted Cauliflower have been famous for!)
Unlike other casseroles with this veggie, this one doesn’t get soggy or mushy on you.
The trick?! Cauliflower is cut into bite-sized florets and then ROASTED in the oven. (Much like in this Roasted Cauliflower recipe.)
You’ll have plenty of room in your tummy to enjoy those yummy Thanksgiving dinner side dishes and pumpkin pie.
What Does “au Gratin” Mean?
“Au Gratin” is a French word that simply means “by grating.” It normally means the dish is topped with grated cheese and/or breadcrumbs and then baked until browned. Popular variations are made with potatoes or cauliflower, sometimes referred to as simply “Potato Gratin” or “Cauliflower Gratin”.
Ingredients
For the exact measurements and detailed instructions, you can jump to the recipe.
- Cauliflower. You’ll need one large head of cauliflower, about 3 pounds, to give you roughly 5 cups of chopped florets.
- Flour. If you’re gluten-free, you can use a 1-to-1 blend, but all purpose works great if not.
- Milk. Oat milk was tested in this recipe to reduce the amount of dairy while keeping things thick. Heavy cream or regular whole milk may also be substituted. Almond milk is too thin, and the taste of coconut milk will be overpowering so avoid these.
- Shredded Cheese. The best shredded cheese for this homemade cheese sauce is Gruyere. Shredded mozzarella, mild cheddar, Swiss cheese or white cheddar will also work.
- Parmesan. A little bit of Parmesan cheese is mixed into the sauce as well as sprinkled on top for a delightful crunch.
- Breadcrumbs. Panko breadcrumbs add to the crunchy texture. If keto, either leave them out or substitute with pork-rind crumbs.
- Spices & Herbs. A hint of dried thyme and a bit of ground coriander accent the cheeses selected. Feel free to get a little creative and try out dried rosemary and tarragon or a sprinkle of ground nutmeg, instead.
How to Make a Cauliflower au Gratin
Jump to the recipe for the full instructions, ingredient amounts, and a printable recipe.
- Prepare and roast the cauliflower. Make the pieces as close to the same size as possible. Larger florets will give you a crunchier bite while smaller florets tend to overcook easily. It’s best if you make your florets no smaller than about 1-inch in size. Toss the florets in olive oil, salt, and pepper. Then bake in an even layer in a 13 by 9-inch baking or casserole dish at 450°F for 15-20 minutes.
- Make the creamy sauce. Whisk together the garlic, butter, and flour together in a medium saucepan or large skillet over medium heat. It is extremely important you whisk it over heat until it is nice and thick. Slowly add in room temperature milk ¼-cup at a time. After each addition of milk, whisk the sauce until it is smooth and begins to thicken. This will take 3-5 minutes. Then, mix in the shredded cheese, seasonings, and half of the Parmesan cheese. Stir until well combined.
- Assemble the casserole. Pour the cheesy sauce over the cooked cauliflower and toss to combine. Mix together the remaining Parmesan cheese and breadcrumbs in a small bowl and sprinkle over the cauliflower.
- Bake and serve. Cook the dish at 400°F for 20-25 minutes. It should be golden brown on the top. Serve this side with your favorite protein.
FAQs
Cauliflower gratin is low in carbs and features cauliflower, which is a fantastic vegetable you can feel good about eating. However, the cheese included contains fat which can be considered unhealthy depending on your dietary needs.
Yes, you can easily prep the day before. Wash and cut the cauliflower, then store it in an airtight container in the refrigerator for up to 3 days.
You can freeze sealed cauliflower gratin for up to 3 months. Just know that the texture will change.
Watery cauliflower gratin can be caused by a number of reasons. If you boiled the veggie instead of roasting you will likely end up with too much moisture. Other causes include if you used too much milk, or if you didn’t wait for the cheese sauce to thicken up.
Other Holiday-Worthy Side Dishes
When entertaining during the holidays and special occasions, the food is the star of the show! Whip up any of these sides next to the main dish to impress anyone at the table.
Scalloped Potatoes and Sweet Potatoes au Gratin are to die for.
Keep things light with a Roasted Beet Salad with Goat Cheese or a Shaved Brussels Sprouts Salad.
And don’t miss out on Bacon-Wrapped Asparagus or Crispy Smashed Brussels Sprouts.
More Cauliflower Recipes
If you loved this creamy dish, get the most out of this vegetable by trying it in a variety of recipes!
Garlic & Herb Whole Roasted Cauliflower, Air Fryer Cauliflower, and Roasted Cauliflower are super simple.
Roasted Garlic Mashed Cauliflower, Cauliflower Soup, and Garlic Parmesan Roasted Broccoli and Cauliflower take a little more time but are totally worth it.
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Cauliflower au Gratin Recipe
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Ingredients
- 1 large head cauliflower cut into florets, about 5 cups
- 2 tablespoons oil olive or avocado
- 1 teaspoon salt divided
- ¼ teaspoon black pepper
- 2 tablespoons butter or oil
- 2 cloves garlic crushed
- 2 tablespoons flour gluten-free 1-to-1 blend
- 1 ½ cups milk regular or cashew milk
- ¾ cup cheese gruyere, asiago, or mixed
- ½ cup Parmesan cheese grated, divided
- ¼ teaspoon dried thyme
- ¼ teaspoon coriander
- ¼ cup Panko bread crumbs gluten-free, optional
Instructions
- Preheat oven to 425°F.
- Prepare the Cauliflower. Add cauliflower florets to a 13 by 9-inch baking dish along with 2 tablespoons of oil, ½ teaspoon salt, and ¼ teaspoon black pepper. Toss to combine and spread cauliflower out in the dish. Bake in preheated oven for 15-20 minutes.1 large head cauliflower, 2 tablespoons oil, 1 teaspoon salt, ¼ teaspoon black pepper
- Make the Sauce. While cauliflower is baking, add 2 tablespoons of butter and crushed garlic to a large skillet or saucepan. Sauté over medium heat for 1 minute. Sprinkle flour into the pan and whisk for 1-2 minutes, or until it begins to form a paste. Reduce heat to medium-low. Pour in room-temperature milk, ¼ cup at a time, whisking well after each addition. Wait to add the next amount until the sauce has thickened.2 tablespoons butter, 2 cloves garlic, 2 tablespoons flour, 1 ½ cups milk
- Add Cheese and Cauliflower. Once all of the milk is added, turn off the heat and mix in gruyere cheese, ¼ cup Parmesan cheese, ½ teaspoon salt, thyme, and coriander. Pour sauce over baked cauliflower and toss to combine.1 teaspoon salt, ¾ cup cheese, ½ cup Parmesan cheese, ¼ teaspoon dried thyme, ¼ teaspoon coriander
- Top and Bake. Mix together remaining Parmesan cheese and breadcrumbs in a small bowl. Sprinkle over cauliflower. Reduce oven temperature to 400 °F and return cauliflower dish to oven for 20-25 minutes. For an extra crispy topping, broil casserole for 2-3 minutes under a high broil.¼ cup Panko bread crumbs, ½ cup Parmesan cheese
- Serve with cauliflower with fresh thyme and enjoy!
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Notes
- Ingredients: Freshly shredded cheese is the best option.
- Size: Large pieces of cauliflower give the crunchiest bite while small pieces might overcook.
- Prep-Ahead: Follow all of the instructions up to sprinkling on the topping. Cover and refrigerate, with the topping stored in a separate container. Pull it out at least 1 hour before baking to allow it to come to room temperature. Sprinkle the topping over the cauliflower and follow the remaining steps for baking it in the oven.
- Storage: This cauliflower gratin tastes best when it is served immediately. You can save covered leftovers in the refrigerator for up to 3-5 days. Just note it will get soggy and not have the same incredible texture. Take it out of the fridge 30 minutes ahead of time, then bake at 350°F for 10-20 minutes.
- Freezing: Freezing is not recommended as it will become very watery upon thawing.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
