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 healthy vegetarian casserole for Thanksgiving, Christmas, or any holiday dinner when you want to impress!

Baked cauliflower gratin is top with fresh herbs for a keto friendly side.

The BEST Cauliflower au Gratin Recipe

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 cauliflower casseroles, 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.)

Yup! No boiling or steaming! Roasting the cauliflower in the oven cooks it without making the dish too water. (Plus, it gets so much more flavor!)

It’s then covered in a creamy Gruyere cheese sauce, topped with a Parmesan-breadcrumb mixture, and broiled until golden and crispy. This cauliflower au gratin recipe has the classic flavor you love but is actually better for you!

Leaving you more 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”.

Cauliflower, cheese, milk, butter, flour, garlic, and bread crumbs are the ingredients in Cauliflower au Gratin recipe.

Ingredients

  • 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.
5 Secrets to Healthier Family Dinners
Tips & recipes for getting yummy — and healthy — meals on the table.

How to Make a Cauliflower au Gratin

Please see the recipe card below for more detailed ingredient amounts.

1. Prepare & Roast Cauliflower

When cutting the head cauliflower into florets, you’ll want to make them as close to the same size as possible. Larger florets will give you a crunchier bite while smaller florets tend to overcook easily. So it’s best if you make your florets no smaller than about 1-inch in size.

Toss the cauliflower 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.

Cauliflower florets are placed in a casserole dish.

2. Make the Creamy Sauce

You’ll first start by whisking together a bit of 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. This paste acts as the binder for the sauce.

Slowly add in room temperature milk ¼-cup at a time. If needed, heat it in the microwave for 30 seconds, or leave it out at room temperature for 30 minutes before cooking. After each addition of milk, whisk the sauce until it is smooth and begins to thicken. Repeat this process over the course of 3-5 minutes. 

Then, mix in the shredded cheese, seasonings, and half of the Parmesan cheese. Stir until well combined. 

Gruyere cheese is then added to the milk and whisked in until melted.

3. 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.

Reduce the oven temperature to 400°F and return the cauliflower dish to the oven for 20-25 minutes. It should be golden brown on the top.

The breadcrumb mixture is sprinkled over the cauliflower and cheese

Is cauliflower gratin healthy? 

Cauliflower gratin is low in carbs and features cauliflower, which is a healthy vegetable. However, the cheese included contains fat which can be considered unhealthy depending on your dietary needs. 

FAQs

Can I prep cauliflower the day before? 

Yes, you can easily prep the cauliflower the day before. Wash and cut the cauliflower, then store it in an airtight container in the refrigerator for up to 3 days. 

Can I freeze cauliflower gratin? 

You can freeze sealed cauliflower gratin for up to 3 months. Just know that the texture will change. 

Why is my cauliflower au gratin watery? 

Watery cauliflower gratin can be caused by a number of reasons. If you boiled the cauliflower 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.

Recipe Tip

  • Pop it under the broiler. Do this during the last 3-5 minutes of cooking to get a crispy brown crust.
  • Similar in size. Cut the cauliflower florets uniformly so they cook up evenly.
  • Do not cover. Sealing the dish with foil while baking will trap in all of the excess moisture and make it soggy.
  • Splurge for Gruyere. This cheese has a unique flavor that pairs well with cauliflower in this cheesy casserole.
  • Sprinkle with fresh herbs. Garnish just before serving for an impressive presentation. 
Keto cauliflower gratin is served with a wooden spoon from a casserole dish.

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 cauliflower au gratin, get the most out of this healthy vegetable by trying it in a variety of recipes!

Garlic & Herb Whole Roasted CauliflowerAir Fryer Cauliflower, and Roasted Cauliflower are super simple.

Roasted Garlic Mashed CauliflowerHealthy Cauliflower Soup, and Garlic Parmesan Roasted Broccoli and Cauliflower take a little more time but are totally worth it.

Tap stars to rate!

4.75 from 4 votes

Cauliflower au Gratin Recipe

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.
Yield 8 servings
Prep 10 minutes
Cook 45 minutes
Total 55 minutes

Ingredients 

  • 1 large head cauliflower cut into florets, about 5 cups
  • 2 Tbsp. oil olive or avocado
  • 1 tsp. salt divided
  • ¼ tsp. black pepper
  • 2 Tbsp. butter or oil
  • 2 cloves garlic crushed
  • 2 Tbsp. 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 tsp. dried thyme
  • ¼ tsp. 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 Tbsp. oil, 1 tsp. salt, ¼ tsp. 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 Tbsp. butter, 2 cloves garlic, 2 Tbsp. 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 tsp. salt, ¾ cup cheese, ½ cup Parmesan cheese, ¼ tsp. dried thyme, ¼ tsp. 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!

Tap stars to rate!

4.75 from 4 votes

Video

Notes

To 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.
To Store: 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.
To Freeze: Freezing is not recommended as it will become very watery upon thawing. 
 
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Nutrition

Calories: 156kcal, Carbohydrates: 7g, Protein: 7g, Fat: 12g, Saturated Fat: 5g, Cholesterol: 19mg, Sodium: 596mg, Potassium: 208mg, Fiber: 2g, Sugar: 2g, Vitamin A: 223IU, Vitamin C: 31mg, Calcium: 263mg, Iron: 1mg

Nutrition information is automatically calculated, so should only be used as an approximation.

Made this recipe?Leave a comment below!
5 Secrets to Healthier Family Dinners
Tips & recipes for getting yummy — and healthy — meals on the table.

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