Roasted Cauliflower Gratin is a creamy baked side dish made with tender roasted cauliflower in a rich Gruyère and Parmesan sauce, topped with buttery Panko breadcrumbs. Serve as a holiday side dish or alongside Vegan Homestyle Meatloaf and Green Bean Bundles for a well-balanced meal.
Easy Holiday Side Dish
I love a good gratin for the holidays, especially one that feels indulgent but is still fairly simple to pull together. Unlike traditional cauliflower au gratin, which is made entirely on the stove, this version starts with roasted cauliflower for richer flavor and better texture.
This creamy cauliflower gratin elevates a classic vegetable in a way that’s elegant for Thanksgiving, Christmas, or Easter but easy enough for everyday dinner.
Ingredients for Roasted Cauliflower Gratin
Here’s what you’ll need. Exact amounts are listed in the printable recipe card at the bottom of the post.
- Cauliflower – Cut into small, even florets about 1½ inches each so they cook evenly and fit well in the baking dish.
- Shallot and Garlic – Dice the shallot finely and mince the garlic small. They’ll soften into the butter and flavor the sauce without visible chunks.
- Butter – Butter gives the sauce a smooth texture and browns the breadcrumb topping nicely.
- Flour – Regular all-purpose flour works best here. Whisk it in well so the sauce stays smooth and free of lumps.
- Heavy Cream and Milk – This combination makes the sauce creamy without being too thick or heavy.
- Lemon Juice – Just a little to balance the richness of the sauce.
- Gruyère and Parmesan – Shred both from a block for better melting.
- Panko Breadcrumbs – For a light, golden finish.
- Nutmeg – Just a small pinch goes a long way. It blends into the sauce and brings warmth without standing out.
How to Make Roasted Cauliflower Gratin
STEP ONE: Prep.
Preheat the oven to 425°F. Line a rimmed baking sheet with parchment paper and lightly grease an 8×8-inch baking dish.
STEP TWO: Roast the Cauliflower.
Add the florets to a large bowl. Drizzle with olive oil, ½ teaspoon salt, and ½ teaspoon black pepper. Stir to coat. Spread on the baking sheet and roast for 15 minutes, until just fork-tender. Set aside and lower the oven temperature to 400°F.
STEP THREE: Make the Sauce.
Melt butter in a medium saucepan over medium heat. Add the shallot and cook about 3 minutes, until softened. Add the garlic and cook 30 seconds more. Whisk in the flour, 1/2 teaspoon salt, 1/2 teaspoon black pepper, and nutmeg. Slowly whisk in the heavy cream, milk, and lemon juice. Continue whisking until slightly thickened, about 1 minute. Remove from the heat and stir in 2 tablespoons Parmesan and all the Gruyère until smooth.
STEP FOUR: Assemble.
Add the roasted cauliflower to a large bowl. Pour the sauce over top and stir gently to coat. Transfer to the prepared baking dish.
STEP FIVE: Add the Topping.
In a small bowl, combine the Panko breadcrumbs, remaining 2 tablespoons Parmesan, and 1 tablespoon melted butter. Sprinkle evenly over the top.
STEP SIX: Bake.
Bake, uncovered, for 15 minutes, until golden and bubbling. Let stand 5 to 10 minutes for the sauce to set, then serve warm.
Make It Vegan 🌱
For a plant-based gratin, use non-dairy butter, heavy cream, milk, and cheeses. I recommend a mild-flavored plant milk like oat milk; other varieties tend to have too much of a flavor undertone. Vegan Parmesan is widely available, but I haven’t found vegan Gruyère in stores yet. However, vegan Swiss cheese works well as a substitute and melts nicely.
Can Cauliflower au Gratin be Made Ahead?
Baked cauliflower gratin is best served the same day, but you can assemble the casserole up to a day in advance if needed. Keep it covered in the refrigerator and wait to add the topping until right before baking.
Storage and Reheating
- Store leftovers in an airtight container in the refrigerator. Reheat in a 350°F oven until warmed through and crisp on top again.
More Side Dish Recipes You’ll Love!
- Cheesy Ranch Cauliflower
- Cauliflower Gratin (No Cheese Sauce)
- Garlic and Sage Roasted Cauliflower
- Roasted Cauliflower Soup
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Roasted Cauliflower Gratin Recipe
Ingredients
- 1 1/2 pounds cauliflower florets
- 1 tablespoon olive oil
- 1/2 teaspoon kosher salt divided
- 1 teaspoon ground black pepper divided
- 2 tablespoons butter
- 1/2 cup shallot diced
- 2 teaspoons garlic minced
- 1 1/2 tablespoons all-purpose flour
- 1/8 teaspoon ground nutmeg
- 1 cup heavy cream
- 1/2 cup milk
- 1 tablespoon lemon juice
- 4 tablespoons Parmesan cheese finely grated and divided
- 1/2 cup Gruyere cheese grated
- 1/4 cup Panko breadcrumbs
- 1 tablespoon butter melted
Instructions
- Preheat the oven to 425°F. Line a rimmed baking sheet with parchment paper and lightly grease an 8×8-inch baking dish.
- Add the cauliflower florets to a large bowl. Drizzle with olive oil, ½ teaspoon salt, and ½ teaspoon black pepper. Stir to coat. Spread on the baking sheet and roast for 15 minutes, until just fork-tender. Set aside and lower the oven temperature to 400°F.
- Melt butter in a medium saucepan over medium heat. Add the shallot and cook about 3 minutes, until softened. Add the garlic and cook 30 seconds more. Whisk in the flour, 1/2 teaspoon salt, 1/2 teaspoon black pepper, and nutmeg. Slowly whisk in the heavy cream, milk, and lemon juice. Continue whisking until slightly thickened, about 1 minute. Remove from the heat and stir in 2 tablespoons Parmesan and all the Gruyère until smooth.
- Add the roasted cauliflower to a large bowl. Pour the sauce over top and stir gently to coat. Transfer to the prepared baking dish.
- In a small bowl, combine the Panko breadcrumbs, remaining 2 tablespoons Parmesan, and 1 tablespoon melted butter. Sprinkle evenly over the top.
- Bake, uncovered, for 15 minutes, until golden and bubbling. Let stand 5 to 10 minutes for the sauce to set, then serve warm.
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