Table of Contents
  1. Why this recipe works.
  2. Everything you’ll need to make this recipe.
  3. Here’s how to make this recipe.
  4. These pro tips will make this recipe a success.
  5. Frequently asked questions about this recipe.
  6. You'll love these other Thanksgiving side dishes.
  7. Watch how to make this recipe.
  8. Have I convinced you to make this recipe?
  9. Cauliflower au Gratin Recipe

This is a decadent dish that’s perfect for the Thanksgiving table. Creamy and flavorful cheese sauce poured over roasted cauliflower forms a perfect pairing. It’s quick and can be created early and baked right before serving, which is great for hectic holiday preparations.

Why this recipe works.

Thanksgiving and all of the holidays are times that we make extra effort and use recipes that are not everyday foods. An au gratin uses cheese, butter, and breadcrumbs to create a sumptuous dish. Often used with potatoes, the same principle can be applied to cauliflower. The key is in the texture of the cauliflower. Instead of cooking the vegetable in water, this recipe roasts it for a crisp-tender texture. Once mixed with a quick cheese sauce and topped with buttery breadcrumbs, the perfect holiday side dish is baked. This is one that will wow and satisfy even the pickiest eater. Welcome to your new favorite side dish.

White baking dish filled with baked cauliflower au gratin with crispy golden brown topping with spoon scooping out a serving.

Everything you’ll need to make this recipe.

  • Cauliflower is roasted to create the perfect texture. Crispy vegetables can withstand the heavy flavors of cheese and butter.
  • Gruyère cheese is the iconic cheese used in au gratins for its slightly nutty and buttery flavor.
  • Nutmeg is often used in cheese sauces to bring out the complex flavors of the cheese. A small amount goes a long way in adding immense flavor without being overpowering.
  • Fresh breadcrumbs add the texture and consistency needed to absorb some of the butter for a toasty topping.
White surface filled with all ingredients needed to make cauliflower au gratin including cauliflower, spices, cheese, milk, breadcrumbs, and more.

Here’s how to make this recipe.

  1. Roast the cauliflower. Take the heads of cauliflower and break them down into small florets. Place them on a large sheet pan. Drizzle the olive oil over the cauliflower and work it in with your hands, then spread the vegetables into an even layer. Season with kosher salt and black pepper. Place into a 425°F oven for 12 to 18 minutes or until the cauliflower is crispy and golden brown.
  1. Prepare the sauce. Place the butter in a saucepan over medium heat. Dice the onion and add to the butter. Cook until the onion becomes slightly translucent and soft, about 4 to 6 minutes. Mince garlic and add with the onion. Cook for a few seconds, just heating the garlic. Add kosher salt and black pepper. Place in the flour and cook for about 1 to 2 minutes, just enough time to break it down. Stir in the milk and cook until it simmers throughout, then remove from the heat. Add in the gruyere cheese, reserving some for garnish. Add in the Dijon and grate in the nutmeg. Stir and let the cheese melt into the sauce.
  1. Assemble the dish. Add the roasted cauliflower to a 9×13 or 8×11 baking dish. Pour the cheese sauce evenly over the cauliflower. Top the rest of the dish with gruyere and Parmesan cheese. In a small bowl, combine the melted butter, breadcrumbs, and black pepper. Sprinkle on top of the dish. Place into a 375°F oven for 25 to 30 minutes until the dish is golden brown.

These pro tips will make this recipe a success.

  • When breaking down the cauliflower, pieces of the stem can also be included in the dish. However, keep the core out. But while it won’t work well in this dish, it can still be eaten. Peel off some of the outer layers of the core, and you have the perfect snack!
  • When adding the garlic to the sauce, make sure not to overcook it. The minced garlic is small, so it cooks quickly; it just needs a few seconds to warm. If it gets overcooked, the taste will become bitter.
  • When adding the milk, stir it in ¼ to ½ cups at a time. This extra time creates a smoother sauce in the end.
White baking dish filled with cauliflower au gratin with crispy browned topping along with cheese.

Frequently asked questions about this recipe.

Can other cheeses be added to this?

Yes, the cheese can be adjusted for personal preference. Make sure to note that each cheese will change the flavor profile and melt at various rates, and the recipe will need to be adapted accordingly.

How early can this dish be prepared?

The cheese sauce can be poured over the prepared cauliflower and can be chilled for up to 6 to 8 hours before finishing with breadcrumbs and baking.

How long does this keep after serving?

This au gratin recipe is best when served fresh. But the leftovers will last for 7 to 10 days in the refrigerator.

Watch how to make this recipe.

More Thanksgiving side dishes

Have I convinced you to make this recipe?

I hope you make this recipe and put some food on your table. Leave a comment and share a star rating so you can let others know how much you love this recipe. This helps show others that this is a recipe they, too, can make, enjoy, and love!

White baking dish filled with cauliflower au gratin after coming out of the oven with browned cheese-covered topping.

Cauliflower au Gratin

5 from 4 votes
This is a decadent dish that's perfect for the Thanksgiving table. Creamy and flavorful cheese sauce poured over roasted cauliflower forms a perfect pairing. It's quick and can be created early and baked right before serving, which is great for hectic holiday preparations.
Prep Time 20 minutes
Cook Time 1 hour
Total Time 1 hour 20 minutes
Servings 8 servings

Ingredients

  • 1 head cauliflower (about 2 ½ to 3 lbs)
  • 3 tbsp unsalted butter divided
  • ½ cup diced onion
  • 4 cloves garlic minced
  • 1 tsp kosher salt
  • ½ tsp black pepper
  • 2 tbsp all-purpose flour
  • 1 ½ cups whole milk
  • ½ tsp grated nutmeg
  • 1 tsp Dijon mustard
  • 1 cup shredded Gruyère cheese divided
  • ½ cup grated Parmesan cheese
  • ½ cup fresh breadcrumbs

Instructions
 

  • Preheat the oven to 425°F. Butter a 9×13 or 8×11 baking dish and set it aside.
  • Clean and cut the cauliflower into bite-sized florets. Spread the florets on two parchment-lined baking sheets. Drizzle with 2 tbsp olive oil, a pinch of kosher salt, and black pepper. Roast in the preheated oven until the cauliflower is tender but not soft and beginning to brown, 12-18 minutes. Once slightly tender, remove the cauliflower from the oven and pour it into the prepared baking dish. Reduce the oven to 375°F.
    1 head cauliflower (about 2 ½ to 3 lbs)
  • Melt 2 tbsp of the butter in a saucepan over medium heat. Once melted, add the onion. Sauté the onion until it is translucent but not brown, 4-6 minutes. Add the garlic and sauté until it is fragrant, 1 minute. Season with the kosher salt and black pepper.
    3 tbsp unsalted butter, ½ cup diced onion, 4 cloves garlic, 1 tsp kosher salt, ½ tsp black pepper
  • Sprinkle in the flour. Stir and cook the flour until it is a paste coating the pan, 1-2 minutes. Using a whisk, slowly add the milk, about ¼ cup at a time, making sure to whisk it smooth before adding more. Once all the milk is added, bring the mixture to a simmer and cook until it is thickened, about 1-2 minutes. Remove from the heat.
    2 tbsp all-purpose flour, 1 ½ cups whole milk
  • Add the nutmeg, Dijon mustard, ¾ cup Gruyère cheese, and Parmesan cheese. Stir until smooth. Pour the sauce over the prepared cauliflower. Sprinkle with the remaining Gruyère and Parmesan cheese. In a bowl, melt the remaining tbsp of butter. Mix the butter with the breadcrumbs and sprinkle them over the cauliflower.
    ½ tsp grated nutmeg, 1 tsp Dijon mustard, 1 cup shredded Gruyère cheese, ½ cup grated Parmesan cheese, ½ cup fresh breadcrumbs
  • Bake in the 375°F oven until the breadcrumbs are toasted and brown, 25-30 minutes. Remove from the oven and serve.

Notes

When breaking down the cauliflower, pieces of the stem can also be included in the dish. However, keep the core out. But while it won’t work well in this dish, it can still be eaten. Peel off some of the outer layers of the core, and you have the perfect snack!
When adding the garlic to the sauce, make sure not to overcook it. The minced garlic is small, so it cooks quickly; it just needs a few seconds to warm. If it gets overcooked, the taste will become bitter.
When adding the milk, stir it in ¼ to ½ cups at a time. This extra time creates a smoother sauce in the end.

Nutrition

Serving: 1servingCalories: 223kcal
Course Side Dish
Cuisine American
Difficulty Easy
Method Baking

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Kaleb

I’m Kaleb! I'm not a chef, professional baker, landscaper, or designer, but I like to play each on Knollgate Farm. Come join me on my journey and let's learn together!

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6 Comments

  1. This looks so delicious I sure am going to make it. I have always looked for a cauliflower au gratin that is not watery and I realize now that roasting it is the key. Thank you very much.

  2. 5 stars
    I am so glad I stumbled on this recipe! I made it for the Thanksgiving dinner we are going to, but I already snuck a bite. Incredibly delicious – worth splurging on the Gruyère for sure. I think this will be a permanent addition to our holiday parties.

  3. 5 stars
    I made this for Thanksgiving dinner and it was delicious and everyone loved it. Will definitely make again- thanks for the recipe!

  4. 5 stars
    Hi Kaleb
    I made this gratin for thanksgiving and it was delicious. I wii be making this dish more than once a year. Thanks for the recipe.