Brussels sprouts gratin with butternut squash is so delicious that even the pickiest of eaters will love it! Made with a luxurious cheese sauce and twice baked with melted gruyere cheese on top. A perfect side dish for any entree!
When it comes to vegetable side dishes, we're all about variety. Just like our recipes for snap peas 3 ways and broccolini 3 ways, this Brussels sprouts gratin with butternut squash is a fresh and unique way to enjoy Brussels sprouts that you may not have tried!
This vegetable casserole is the ultimate comfort food! This dish includes Brussels sprouts and butternut squash, first roasted, then doused in a luxurious cheese sauce with sage and nutmeg. It is twice-baked with gruyere cheese for the ultimate rich and creamy side dish.
You can't go wrong with adding this to your Sunday night dinner, or holiday table!
Reasons you'll love this recipe
- The rich cheese sauce is so good, it will convert even the pickiest eater into a Brussels sprouts fans!
- It's the perfect side dish to add to your holiday table
- It's ready in under an hour, and is easy to prepare
Recipe Video
Watch the video below to see how to cook this brussels sprouts gratin! You can find more of my recipe videos on my YouTube channel and Facebook page.
Ingredient notes
- Veggies: We're using Brussels sprouts and butternut squash. However, you could swap for broccoli, cauliflower, or even sweet potatoes—adjust roasting time as needed.
- Cheese sauce - made with a bit of butter, flour, sage, nutmeg, milk and cheese. For a lower-carb alternative, check the notes in this chicken and cauliflower casserole (almond flour + heavy cream option)
- Cheese - I used gruyere to sprinkle on top and get that cheesy crust. Mozarella or monterey jack would also work if you don't have gruyere!
step by step directions
Prepare Veggies
Heat oven to 425°F. Trim ends off brussels sprouts and slice them in half. Toss with the butternut squash in olive oil, salt & pepper.
Roast
Arrange in a 9 X 13-inch baking dish and roast for 25-35 minutes, until the veggies are soft.
Prepare Cheese Sauce
While vegetables are roasting, make the cheese sauce: In a medium pan, melt the butter over medium heat. Whisk in the sage, nutmeg, salt, and flour. Add the milk gradually over the course of several minutes, whisking so that the flour doesn't clump. Cook until slightly thickened, then stir in ¾ cup of the shredded cheese. Remove from heat when the cheese has melted in and sauce is thickened.
Combine
Once vegetables are tender, pour the sauce over top. Toss veggies in sauce, then sprinkle remaining cheese over top.
bake
Return to the oven for another 10-15 minutes, until sauce is bubbling and cheese is melted. Serve + enjoy!
FAQ
Yes! You could swap for any number of veggies including broccoli, cauliflower, and maybe even sweet potatoes. You may need to adjust the roasting time depending on the veggie.
You should be able to use heavy cream and almond flour. See the notes in this post for the ratio you'll need.
Yes! See below for specific instructions. Not only can you assemble it ahead and finish off right before serving, but you can also enjoy leftovers for several days.
Variations
I make this recipe every year! Here are some ways I've done it:
- Double the Brussels sprouts and leave out the butternut squash
- Double the sauce for extra flavor
- Cook your Brussels sprouts in the Instant Pot first to save time in the oven; make sure to drain well
- Swap the brussels sprouts for cauliflower (see cauliflower gratin)
- Swap the gruyere for mozzarella
Storage & Reheating
- Fridge - Store in a covered container in the fridge for up to 4 days; the brussels sprouts don't smell good but still taste great.
- Reheat - Heat in the microwave until steaming hot or bake in a covered casserole dish in the oven at 350°F for about 20 minutes or until warmed through.
Preparing ahead
This recipe can be cooked almost all the way ahead, brought to where you'll eat dinner, then finished off in the oven just before serving. Here's how to do it:
- Complete steps 1-4, but do not bake.
- Cover, then keep in the fridge until you're ready to serve (best done the same day you prepare).
- Heat oven to 425°F. Uncover, and heat for 15-20 minutes, until cheese is melted and sauce is bubbly *
*depending on how cold your dish is going into the oven, you might need to increase or decrease the cook time.
Did you make this? Tag me on social @sweetpeasandsaffron and be sure to leave a comment and rate the recipe!
Brussels Sprouts Gratin with Butternut Squash
Ingredients
- 24 oz brussels sprouts ends trimmed and sliced in half
- 20 oz butternut squash peeled & chopped into 1 inch cubes
- 2 tablespoons olive oil
- 1 ½ tablespoon unsalted butter 21 g
- 1 teaspoon dried sage leaves crumbled
- ⅛ teaspoon nutmeg
- ¾ teaspoon salt
- 1 ½ tablespoons all purpose flour 23 g
- 1 cup 2% milk
- 1 ¼ cups shredded cheese divided; mozzarella works but go for gruyere if you can
Instructions
- Prepare veggies - Heat oven to 425°F. Trim ends off brussels sprouts and slice them in half. Toss with the butternut squash in olive oil, salt & pepper.
- Roast - Arrange in a 9 X 13-inch baking dish and roast for 25-35 minutes, until the veggies are soft.
- Prepare Cheese Sauce - While vegetables are roasting, make the cheese sauce: In a medium pan, melt the butter over medium heat. Whisk in the sage, nutmeg, salt, and flour. Add the milk gradually over the course of several minutes, whisking so that the flour doesn't clump. Cook until slightly thickened, then stir in ¾ cup of the shredded cheese. Remove from heat when the cheese has melted in and sauce is thickened.
- Combine - Once vegetables are tender, pour the sauce over top. Toss veggies in sauce, then sprinkle remaining cheese over top.
- Bake - Return to the oven for another 10-15 minutes, until sauce is bubbling and cheese is melted.
Tips:
- you can replace the butternut squash for an equivalent amount of brussels sprouts
- rather than roasting, you can cook the brussels sprouts in the Instant Pot; drain well
- sometimes we double the sauce on this recipe for an extra-indulgent side dish
- Complete steps 1-4, but do not bake.
- Cover, then keep in the fridge until you're ready to serve (best done the same day you prepare).
- Heat oven to 425°F. Uncover, and heat for 15-20 minutes, until cheese is melted and sauce is bubbly *
- Fridge - Store in a covered container in the fridge for up to 4 days (best enjoyed within 2).
- Reheat - Heat in the microwave until steaming hot or bake in a covered casserole dish in the oven at 350°F for about 20 minutes or until warmed through.
Video
Nutrition Information
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Denise says
Hi Nancy! I bet it they would work, although I really can't say for sure without re-testing. If you try, I'd love to hear how it turns out for you!