Serve this mouthwatering Brussels Sprouts Casserole (a.k.a. Brussels sprouts bathing in a bubbly, creamy sauce and showered with buttery, crispy bread crumbs), and prepare to win the hearts of veggie-skeptics and veggie-lovers alike.
Another name for this recipe (in addition to “that one side dish no one could stop eating”) would be “Brussels Sprouts Gratin.”
Gratins or au gratin or, if we are being REALLY fancy, gratinée are catch-all terms for something (usually vegetables) baked in a shallow dish (often called a gratin dish) with a lid of cheesy, crispy something (usually breadcrumbs and Gruyère cheese) baked on top.
Gratins are a casserole! If you want to feel fancy, go ahead and call it that.
Or, keep it straightforward and call it cheesy Brussels sprouts casserole. With bacon. (Don’t forget the bacon).
While simple Brussels sprouts preparations, like Roasted Frozen Brussels Sprouts, classic Roasted Brussels Sprouts, or Roasted Brussels Sprouts with Garlic, are perfect for quick-and-dirty weeknights, for a special occasion, I am all for the more elevated experience that this pleasing casserole offers.
This casserole is easy to make. While there are a number of steps, each is straightforward.
I have total confidence that you can pull it off with au gratin-level style.
In keeping with my usual recipe approach, this is a healthy Brussels sprouts casserole (well, healthier than most), but I promise that between the Gruyère cheese, crispy bread crumb topping, and BACON, you won’t notice the lighter tweaks one bit.
5 Star Review
“These were simply divine! These sprouts were just to die for. Well done! Bravo. Adding this to the lengthy list of favorites from your site.”— Diane —
How to Make Brussels Sprouts Casserole
This Brussels sprouts recipe is my take on a Brussels sprouts au gratin with bacon (which I’ve already confessed is a deluxe way of saying “Brussels sprouts casserole with bacon.”)
It has the same creamy, cheesy appeal, and the crispy bacon bread crumb topping takes it to the next level.
Unlike some other recipes I’ve seen, this version creates flavors from scratch. No mushroom soup Brussels sprouts casserole here!
- Brussels Sprouts. These tasty little green veggies are wrapped up in a creamy sauce and baked until delightfully tender and flavorful. Besides being delicious, Brussels sprouts are low in carbs and incredibly healthy. They’re packed with fiber, vitamins, and minerals.
- Butter + All-Purpose Flour. These two come together to create the thick, cheesy, and creamy sauce.
- Milk. I used 2% here, and it added the perfect amount of richness. If you’d like even more decadence, feel free to upgrade to whole milk; skim is less recommended because it could make the sauce too thin.
- Thyme + Nutmeg. Fresh thyme adds savoriness, and nutmeg brings a layer of warmth and coziness. It’s also a classic gratin spice.
- Gruyère Cheese. A melty, slightly nutty, and salty-sweet cheese that pairs beautifully with the bacon and Brussels sprouts.
- Whole Wheat Bread Crumbs + Thick-Cut Bacon. The dreamy topping for our Brussels sprouts casserole. Both the bread crumbs and the bacon become tantalizingly crisp and golden brown.
- Cook the bacon and leave some drippings in the skillet.
- Cook the Brussels sprouts in the drippings with the onions. Add some water and allow the Brussels sprouts to soften. Transfer to a baking dish.
- In the same skillet, prepare the creamy sauce, then pour over the Brussels sprouts.
- Sprinkle bread crumbs and bacon over the top. Bake at 400 degrees F for about 10 to 15 minutes. DIG IN!
Meal Plan Tip
- Prepare the dish through Step 3 up to 1 day in advance. Cover and store it in the refrigerator. When ready to bake, let the dish come to room temperature. Sprinkle with the bread crumbs and bacon and bake as directed.
Brussels Sprouts Casserole Storage Tips
- To Store. Refrigerate Brussels sprouts casserole in an airtight storage container for up to 3 days.
- To Reheat. Gently rewarm leftovers in a baking dish in the oven at 350 degrees F or reheat gently in the microwave.
- To Freeze. Store leftovers in an airtight freezer-safe storage container for up to 2 months. Let thaw overnight in the refrigerator before reheating. The Brussels sprouts will become a little mushy once thawed, but the flavors will still be delicious.
Recommended Tools to Make this Recipe
- Baking Dish. For this Brussels sprouts gratin with bacon and gruyere, you need a heavy-duty baking dish like this.
- Skillet. A high-quality skillet is an essential tool in my kitchen.
- Cheese Grater. Either a box grater or microplane grater will work great.
Brussel Sprouts Casserole
- 3 slices thick-cut bacon
- 2 pounds brussels sprouts trimmed and halved (cut into thirds or quarters if very large—you want the pieces to be roughly the same size)
- 1/2 yellow onion finely diced
- 3/4 teaspoon kosher salt divided
- 1 tablespoon unsalted butter
- 2 tablespoons all-purpose flour
- 1 1/2 cups 2% milk
- 1 tablespoon chopped fresh thyme or 1 teaspoon dried thyme leaves
- 1/4 teaspoon black pepper
- Pinch ground nutmeg optional
- 1/2 cup freshly grated Gruyère cheese sharp white cheddar cheese, or a similar fully flavored, melty cheese
- 1/4 cup whole wheat bread crumbs
- Olive oil cooking spray
- Preheat the oven to 400 degrees F. Lightly coat an 8×12-inch or similar 2-quart glass or ceramic gratin or casserole dish with olive oil cooking spray. Set aside.
- In a large frying pan, cook the bacon over medium-low heat until crisp, about 8 to 10 minutes. (Do not rush it or the bacon will burn before it is fully crispy.) Remove the bacon to a paper-towel-lined plate, pat dry, and let cool. Discard all but 1 tablespoon of the bacon drippings from the pan.
- Place the pan back on the heat and increase the heat to medium high. Add brussels sprouts, onions, and 1/2 teaspoon kosher salt. Stir and cook until the onion is soft and golden and the brussels sprouts are crisp-tender, about 10 to 12 minutes. Add 1/2 cup water. Bring to a boil, then cook until the liquid is evaporated, about 2 to 3 minutes. Spoon the brussels sprouts and onions into the prepared baking dish. Carefully wipe the pan clean.
- Melt the butter in the pan over medium. Once melted, sprinkle the flour over the top and whisk until the flour becomes golden, about 1 minute. Add the milk a few splashes at a time, whisking vigorously as you go to break up any lumps. Once all the milk is added, bring the mixture to a simmer. Continue to simmer, stirring often, until the mixture thickens into a sauce, about 2 to 4 additional minutes. Stir in the thyme, pepper, nutmeg, and remaining 1/4 teaspoon salt. Remove the pan from the heat and stir in the cheese until it melts. Taste and add additional salt or pepper as desired (remember that the bacon will also add some saltiness). Pour over the brussels sprouts, and with a spatula or the back of a spoon, spread the sauce evenly over the top.
- Sprinkle the bread crumbs over the top of the brussels sprouts, then lightly coat the breadcrumbs with olive oil spray. Crumble the bacon, then sprinkle it over the top. Place in the oven and bake until hot and bubbly and the bread crumbs are golden, about 10 to 15 minutes. Serve hot.
- Prepare the dish through step 3 up to 1 day in advance and store covered in the refrigerator. Sprinkle with bread crumbs and bacon just prior to baking.
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