Brussels Sprouts Casserole

Baked Brussels sprouts covered in melted cheese sauce in a white rectangular casserole dish, with some herbs and kitchen items around it.

5 from 4 votes

Brussels Sprouts Casserole

🧀😋 This easy casserole is ready in under an hour and will make everyone a fan of Brussels sprouts! They're roasted to perfection and smothered with cheese and a creamy sauce that'll have everyone asking for seconds! A naturally gluten-free side dish that's great for holiday meals like Thanksgiving, Christmas, or family dinners. Make-ahead directions are provided below in Step 6.

Prep Time15

Cook Time35

Course: Casserole, Side Dish, Sides, Sides, Salads & Vegetables

Cuisine: Sides

Diet: Gluten Free, Vegetarian

Keyword: brussel spout casserole, brussels sprouts casserole, cheesy brussels sprout casserole, creamy brussels sprout casserole

Servings:

Calories: 147cal

Equipment

2.5-quart baking dish
Medium Saucepan (or medium skillet)

Ingredients

1 to 1 ¼ pounds fresh Brussels sprouts trimmed and halved or quartered if they're extra large (discard any leaves that fall off in the trimming process; frozen is not my recommendation based on texture but theoretically you may use frozen that have been thawed and drained)
1 tablespoon olive oil
1 teaspoon kosher salt or to taste
½ teaspoon freshly ground black pepper or to taste
2 tablespoons unsalted butter
2 tablespoons all-purpose flour
1 cup whole milk or half-and-half
½ cup shredded gruyere cheese divided (I strongly recommend it although Swiss cheese or Jarlsberg may be subsituted)
¼ cup grated parmesan cheese divided
1 teaspoon garlic powder
1 teaspoon onion powder
½ teaspoon salt or to taste
¼ teaspoon freshly ground black pepper or to taste
Optional for garnishing: ¾ cup cooked and crumbled bacon sliced green onions or chives, red pepper flakes, fresh herbs, extra cheese, etc.

Instructions

Preheat oven to 425F, and spray a baking dish with cooking spray. Use a 7x11-inch or a 2 to 2.5-quart baking dish, or similar sized.
Roast Sprouts: Place the trimmed Brussels sprouts in the baking dish, evenly drizzle with olive oil, evenly season with 1 teaspoon salt, 1/2 teaspoon pepper, and use clean hands to toss and coat evenly. Roast for about 20 minutes.
Roux: While the sprouts are roasting, make the roux. To a medium or large skillet, add the butter, flour, and cook over medium heat for about 1 minute, stirring continuously, to create the roux. This is what helps the sauce thicken later so don't shortchange this step.
To the lightly golden browned roux, slowly add the milk, whisking continuously as you add it.
Creamy Cheese Sauce: Add HALF the gruyere, HALF the Parmesan, garlic powder, onion powder, 1/2 teaspoon salt, 1/4 teaspoon pepper, and stir continuously to melt the cheeses, about 1-2 minutes.
Remove the Brussels sprouts from the oven, stir and toss them, and evenly pour the cheese sauce over the top.
To Make-Ahead, stop now, tightly cover with foil, and refrigerate for up to 24 hours before baking off. If you're going to do this, make sure to let it sit on your counter for at least 30 minutes to come to room temp before baking because you won't have good results with a fridge-cold casserole.
Evenly sprinkle with the remaining gruyere and the remaining Parm.
Roast with Sauce: Return the baking dish to the oven and bake for about 10-15 minutes, or until the cream sauce and cheese are lightly bubbling, or as golden browned as desired.
Broil, optionally: If you know how to use your broiler and are confident broiling, you may broil the casserole for 1-2 minutes, or as needed, to lightly brown the top. Tip - Whenever broiling, take care not to become distracted because food can go from underdone to burnt in the span of 30 seconds, and you ruin it all. Keep a very watchful eye on it.
Garnish, optionally: With bacon, extra cheese, more salt and pepper, etc. as desired, and serve immediately.

Notes

Storage: Leftovers will keep airtight in the fridge for up to 4-5 days, taking care to reheat it gently in the microwave for about 30 seconds, or as needed, since there's a cheesy cream sauce involved. For that reason, I've never frozen leftovers, although it may be possible.

Nutrition