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Dive into this creamy, cozy, roasted cauliflower gratin which is an easy make-ahead dish and a great alternative to potatoes.
If you’re tired of the same old boring side dishes say hello to this roasted cauliflower gratin. With it’s creamy sauce and roasted, nutty flavor, this veggie dish is equally suited for a weeknight dinner or your holiday table.
Because cauliflower dishes can often be watery (cauliflower is over 90% water!) I prefer to roast it before folding it into a creamy mornay sauce and baking. Roasting draws out the moisture and prevents a mushy gratin.
What’s a mornay sauce you ask?
A mornay sauce is simply a béchamel (flour/butter/milk) with cheese folded into the sauce. It’s seasoned with kosher salt and a sprinkling of nutmeg to taste. I amp up the flavor for this roasted cauliflower gratin by sautéing a small onion and minced garlic before adding in the flour to create the roux.
Then whole milk is whisked into the bubbling roux and brought to a boil and simmered until thickened. Rosemary, parmesan, and nutmeg round out the sauce and sprinkle of salt heightens the flavor. Once the sauce is creamy and thick (all while continuously whisking), the roasted cauliflower is folded in and baked until bubbly.
Making ahead?
You can prepare this gratin right up until popping it in the oven to bake.
- Simply cover the gratin tightly with plastic wrap or foil and refrigerate up to two days.
- Uncover and let it sit at room temperature for 20-30 minutes before baking and serving.
- Note that if baking the gratin right out of the refrigerator will add an additional 5-10 minutes to the baking time.
Let’s make Roasted Cauliflower Gratin
- Cut the cauliflower into florets and place on lined sheet tray. Drizzle with olive oil and season with salt.
- Roast until golden brown. Reserve.
- While the cauliflower is roasting, start the sauce. Saute the onions in butter until translucent.
- Add the garlic and saute for 2 mins.
- Stir in the flour and cook for 2 mins.
- Slowly whisk in the milk. Add the rosemary and nutmeg. Bring to a boil and reduce to a simmer.
- Whisk in the parmesan and season to taste.
- Mix in the roasted cauliflower.
- Scrape the cauliflower mixture into a prepared baking pan and top with Parmesan.
- Bake until hot, bubbly and golden brown. Serve immediately.
Tips for success
- Cut the cauliflower into similar sizes so it roasts evenly.
- When making the sauce, be sure to whisk frequently to prevent lumps and the sauce from sticking to the bottom of the pan.
- Making ahead? You can make this cauliflower gratin through the last step (just before baking) and refrigerate for up to 2 days. Allow an extra 5-10 minutes baking time if baking directly from the refrigerator.
- Don’t skip roasting the cauliflower! Roasting helps to draw out the moisture from the cauliflower which prevents the gratin from becoming watery.
More tasty cauliflower recipes!
- Buffalo Cauliflower Bites
- Creamy Cauliflower Mash
- Sausage Sheet Pan Dinner with Cauliflower and Broccoli
- Lemon Herb Grilled Cauliflower Steaks
- Roasted Cauliflower and Grapes with Yogurt Sauce
- Roasted Fennel and Cauliflower Soup
Dive into this creamy, cozy, roasted cauliflower gratin which is an easy make-ahead dish and a great alternative to potatoes.
- 1 cauliflower head, cut into florets
- 1 Tbsp extra virgin olive oil
- 2 Tbsp unsalted butter
- 1 small onion, diced
- 3 cloves garlic, minced
- 2 Tbsp AP flour
- 2 cups whole milk
- 3 sprigs rosemary
- 1/4 tsp nutmeg, grated (or ground)
- 3/4 cup parmesan cheese, grated + 1 Tbsp for topping
- kosher salt and pepper
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Preheat oven to 425 degrees F. Toss the cauliflower florets with 1 Tbsp olive oil and sprinkle with kosher salt.
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Arrange on a parchment lined sheet tray and roast until golden brown, about 30 mins. Reduce the oven to 375 degrees F.
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While the cauliflower roasts, make the sauce. Heat the butter in a large saucepan over medium heat. Add the diced onion and cook until translucent, about 5 mins.
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Add the garlic and cook 2 mins more. Sprinkle the flour over the onions and garlic and stir. Cook, while stirring, for 2 mins.
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Slowly pour in the milk while vigorously whisking. Add the rosemary sprigs and the nutmeg.
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Bring the milk mixture to a boil and reduce to a simmer, whisking occasionally to prevent it from sticking. Simmer for a minute or two until thickened and continue to whisk.
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Remove from the heat, remove the rosemary sprigs, and stir in 3/4 cup parmesan. Season to taste with kosher salt and pepper.
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Stir the roasted cauliflower into the sauce. Grease a 9 inch square baking dish and pour the cauliflower mixture into the dish. Sprinkle with 1 Tbsp parmesan and and bake until hot and bubbling, about 30 mins. Serve hot.
- Cut the cauliflower into similar sizes so it roasts evenly.
- When making the sauce, be sure to whisk frequently to prevent lumps and the sauce from sticking to the bottom of the pan.
- Making ahead? You can make this cauliflower gratin through the last step (just before baking) and refrigerate for up to 2 days. Allow an extra 5-10 minutes baking time if baking directly from the refrigerator.
- Don’t skip roasting the cauliflower! Roasting helps to draw out the moisture from the cauliflower which prevents the gratin from becoming watery.
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