This lusciously cheesy Broccoli Cauliflower Brussels Sprout Gratin isn’t your average casserole. Ditch the canned cream-of-craziness, grab some veggies, and meet me in the kitchen!
I packed an entire crisper drawer’s worth of vegetables into this holiday-worthy gratin, and it’s absolutely delicious.
While many friends are busy with festive baking, I’m keeping things savory this season. That means less time on cookies and more time showcasing seasonal produce in a way that feels indulgent and comforting.
Broccoli Cauliflower Brussels Sprout Gratin.
This gratin features tender broccoli, cauliflower, and Brussels sprouts bathed in a creamy béchamel with caramelized onions and a melty blend of Gouda and Gruyère, finished with crisp golden breadcrumbs. It’s a side dish designed to impress.
With over two pounds of vegetables in the dish, each bite is rich and satisfying. That’s the beauty of a gratin—fresh vegetables get elevated by a luscious cheese sauce and a crunchy topping.
Ready to fall in love with your veggies?
Broccoli Cauliflower Brussels Sprout Gratin
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Ingredients
- 1 lb cauliflower florets
- 8 oz broccoli
- 8 oz brussels sprouts (quartered)
- 2 cups onion (white or yellow)
- 1 tsp olive oil or butter
- ¼ cup butter
- ¼ cup flour
- ½ cup heavy cream (room temperature)
- 1 cup milk (room temperature)
- 4 oz freshly grated Gruyère cheese
- 4 oz freshly grated Gouda cheese
- ¼ tsp salt
- black pepper to taste
- 1/4-1/2 cup Italian-seasoned breadcrumbs
- 1-2 TBSP butter
Instructions
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Preheat the oven to 350°F (175°C).
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Chop the cauliflower, broccoli, and quarter the Brussels sprouts.
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Bring a pot of water to a boil and blanch the vegetables until the broccoli turns bright green and the vegetables are between al dente and fork-tender, about a few minutes but no longer than 8. Immediately transfer them to an ice bath to stop the cooking if you want them to stay firm. For softer vegetables, cook a bit longer and skip the ice bath.
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Place the blanched vegetables in a casserole dish and set aside.
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In a medium pot, heat the olive oil or a bit of butter and caramelize the onions over medium heat, stirring occasionally, until golden and tender.
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Reduce the heat to medium-low and add 1/4 cup (4 TBSP) butter to the pot.
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Once the butter melts, whisk in the flour a tablespoon at a time to form a roux, stirring constantly so it blends with the onions.
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Gradually whisk in room-temperature or slightly warmed milk and cream until the sauce thickens into a smooth béchamel.
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Remove the pot from the heat and stir in half of the grated cheese until melted and smooth.
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Pour the sauce over the vegetables in the casserole dish, then sprinkle the remaining cheese on top.
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Melt 1 tablespoon of butter in a small skillet, add the breadcrumbs and toast, stirring constantly, until golden. Scatter the toasted breadcrumbs over the casserole.
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Bake on the center rack at 350°F for 20 minutes, until bubbling and the top is golden.
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Serve warm and enjoy.
Notes
Want fewer servings? The recipe scales down easily—simply halve the ingredients.
Nutrition facts are estimated using an online calculator; adjust as needed.
Nutrition
Veggie gratin swaps + substitutions
If your cheese selection is limited, using all Gouda or all Gruyère works well. The combination of both is lovely, but a single cheese will still yield a delicious result.
No heavy cream on hand? You can use all milk. Whole milk or 2% both perform nicely in the sauce.
Love breadcrumbs? Double them. If someone in your group is picky, you can leave out one type of vegetable—broccoli and cauliflower alone make a great gratin, and a large amount of cauliflower is also fantastic.
This recipe is a great way to turn cruciferous vegetables into something everyone reaches for—give it a try.
So… how was it!?
Fantastic. We’ve made this gratin multiple times and adore it. It’s easy, cheesy, and comforting—perfect for warming up a chilly evening with a generous plate of vegetables and melty cheese.