Brussels Sprouts and Mushroom Casserole

Annalise, Completely Delicious

A twist on the classic green bean casserole, this Brussels sprouts and mushroom casserole is a fun way to mix things up this Thanksgiving. It’s made from scratch, giving it that little extra flavor that your Thanksgiving table needs.
20 min Prep Time
25 min Cook Time
  • Prep Time: 20 min
  • Cook Time: 25 min
  • Servings: 12 servings

Servings: 12 servings


  • 6 tablespoons (3/4 stick) unsalted butter, divided
  • 1 1/2 lbs Brussels sprouts, trimmed and halved
  • 8 ounces button or cremini mushrooms, sliced
  • 1 medium onion, chopped
  • Salt and pepper
  • 2 cloves garlic, minced
  • 2 tablespoons all-purpose flour
  • 1 cup chicken or vegetable stock
  • 1 cup half and half
  • 1 cup panko breadcrumbs
  • 1 6-ounce can French fried onions


Step 1

Preheat oven to 375°F. Butter a 9x13-inch casserole dish. Set aside.

Step 2

Melt 2 tablespoons butter in large skillet set over medium heat. Add Brussels sprouts and cook until browned, about 5 minutes. Transfer to separate bowl and set aside.

Step 3

Add mushrooms and onions to skillet, season with salt and pepper, and cook until soft, about 5-6 minutes. Add garlic and cook for 1 minute more. Add to bowl with Brussels sprouts.

Step 4

Melt 2 tablespoons butter in medium skillet. Add flour and whisk to form thick paste. Add chicken or vegetable stock gradually while whisking constantly. Whisk in half and half. Increase heat to medium high and bring to boil, whisking frequently. Simmer for about 5 minutes until thickened. Season with salt and pepper to taste.

Step 5

Combine Brussels sprouts mixture with sauce and pour into prepared casserole dish. Melt remaining 2 tablespoons of butter and combine with breadcrumbs in medium bowl. Add French fried onions. Scatter mixture on top of Brussels sprouts mixture and bake casserole until bubbly and topping is brown, about 20-25 minutes.
Note: This casserole can be prepared ahead of time. Cover unbaked casserole with plastic wrap and chill in the fridge for up to 1 day. Remove plastic wrap and bake, increasing time to 35-40 minutes.