Brussels Sprouts Gratin

Roasted until tender then covered with a rich, cheesy sauce, Brussels sprouts gratin is a delicious side dish for any main course.

Most of us think of potatoes when we think of gratin. Potatoes are smothered with a creamy sauce that gets a little crispy in the oven. Simply delicious. It is the sort of dish that makes me forget about the main course at a holiday table and just reach for the vegetables.

But potatoes don’t get all the fun. Lots of veggies can be made indulgent and wonderful with the gratin treatment.


Brussels Sprouts: Select firm, green sprouts of fairly uniform size.

Salt & Pepper: Used to flavor the sprouts.

Butter: Butter is used to sauté the onion and combine with the flour to thicken the sauce.

Onion: I typically use red onion as that is what I have available. Yellow or white onions are also a great option.

Flour: Used to thicken the sauce.

Milk and Half & Half: This combination provides the base for the luscious creamy sauce that covers the sprouts.

Thyme: Thyme is such a lovely, versatile spice. It complements the cheese sauce perfectly.

Gruyère or Swiss Cheese: I have made the recipe with both kinds of cheese, and it is scrumptious with either. Gruyère adds an especially nice nutty flavor to the sauce.

Parmesan Cheese: Adds a flavorful, salty bite to the sauce.


Start by prepping the sprouts. Remove any yellowing or otherwise discolored leaves and slice the sprouts in half. The goal is pieces that are fairly uniform in size, so they roast and get tender at the same time. If your sprouts are different sizes, you may need to quarter some of them.

Season and bake, tossing them once during the baking process.

While the sprouts are baking, start making the sauce. Melt butter and sauté the onions. You will then make a roux, which is a creamy white sauce. Sprinkle flour over the butter and stir until the flour is incorporated. Add the milk and half & half and stir. The mixture will thicken as it cooks.

Once the sauce had thickened, add the thyme and cheese. Stir until the sauce is smooth, and the cheese had melted.

Pull the Brussels sprouts from the oven and pour the cheese sauce evenly over the sprouts. Sprinkle with parm and bake until the gratin is bubbly and lightly brown.

Plate yourself a generous coop of Brussels sprouts gratin and enjoy every bite!

For more great recipes that feature these tasty little veggies, try this Asian glazed variety or this creamy parm version.

Brussels Sprouts Gratin

Prep Time 10 minutes
Cook Time 40 minutes
Course Side Dish
Cuisine American
Servings 3


  • 1 pound Brussels sprouts trimmed of outer leaves and sliced in half
  • ¼ tsp salt
  • ¼ tsp fresh ground black pepper
  • 1 Tbsp butter
  • ½ cup onion chopped
  • 1 Tbsp flour
  • ½ cup milk
  • ¼ cup half & half
  • 1 tsp thyme
  • ¾ cup Gruyere or Swiss cheese shredded
  • freshly grated parmesan cheese


  • Preheat oven to 400℉. Spray a shallow casserole dish with cooking spray.
  • Add the Brussels sprouts and season with salt and pepper. Spray more olive oil over the sprouts and place in the lower third of the oven. Bake 15 minutes, toss and bake an additional 10 minutes.
  • Heat a medium saucepan over medium to low heat. Melt and butter and add the onion, sauté the onion until softened, about 4 to 5 minutes. Sprinkle the flour over the onion and stir until the flour is incorporated. Add the milk and half & half and stir until the mixture is combined. Cook over medium-low heat for about 4 minutes, stirring, until the sauce is thickened and bubbly.
  • Add thyme and half of the grated Gruyere cheese into the sauce and stir until the cheese is melted and incorporated into the sauce.
  • Pour the sauce over the baked Brussels sprouts, and top with the remaining cheese and the grated parmesan. Bake for 15 minutes until top is lightly browned and bubbly.
Keyword Casserole, cheesy, Creamy, Savory

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