Cheesy Bacon Brussels Sprout Casserole
This cheesy Brussels sprout casserole turns the humble vegetable into a rich, bubbly main dish studded with bacon and topped with crunchy fried onions. It is fast enough for a weeknight, the kind of recipe that disappears fast and even converts the skeptics at the table.
The creamy sauce wraps around every leaf, and the nutmeg, Gruyère, and bacon do the heavy lifting so no one thinks about boiled sprouts. You get a crisp, savory topping without any extra fuss.
What Makes This Casserole a Keeper
The sauce is just thick enough to coat the sprouts without turning gummy, and the bacon fat we cook everything in gives the dish a deep, savory backbone. You get a little char on the sprout cut sides, a lot of cheesiness, and a loud crunch from the fried onions on top.
It also comes together in one skillet if yours is oven-safe. Fewer dishes, shorter cleanup, and still something that feels indulgent on a Tuesday.
Ingredients
- 1 ½ lbs Brussels sprouts: trimmed and halved, small to medium ones work best
- 6 slices bacon, diced: thick-cut gives you meatier bits in each bite
- 1 small yellow onion, diced
- 2 cloves garlic, minced
- 1 tbsp all-purpose flour
- 1 cup whole milk
- ½ cup heavy cream
- ½ tsp kosher salt
- ¼ tsp black pepper
- ¼ tsp ground nutmeg
- 1 cup shredded Gruyère cheese: from a block so it melts smoothly
- ½ cup crispy fried onions (such as French’s)
Variations / Substitutions
- Protein swap: use pancetta or cooked sausage crumbles instead of bacon
- Cheese swap: sharp cheddar or fontina melt just as well, the flavor will be slightly sharper
- Add mushrooms: sauté 4 oz sliced cremini with the onion for an earthier bite
- Vegetarian version: skip the bacon and cook the vegetables in 2 tbsp butter with a pinch of smoked paprika
Kale and Brussel Sprout Salad goes great with this casserole when you want something fresh on the side.
How to Make Cheesy Bacon Brussels Sprout Casserole
Step 1: Cook the Bacon
Preheat your oven to 375°F (190°C) now so it is ready when you need it. Scatter the diced bacon in a large oven-safe skillet and set it over medium heat. Cook, stirring occasionally, until the pieces are crisp and deeply browned, about 6 to 8 minutes.
Use a slotted spoon to lift the bacon onto a paper towel-lined plate, leaving 2 tablespoons of the fat in the pan. If the bacon rendered more, pour off the excess but do not wipe the skillet clean, those browned bits carry flavor.
Step 2: Sauté the Sprouts and Onion
Add the halved Brussels sprouts to the hot skillet, cut-side down, and scatter the diced onion around them. Let them sit untouched for 3 to 4 minutes over medium-high heat. You want the bottoms to turn a deep golden brown while the tops stay bright green.
Once the flat sides are caramelized, stir everything together and cook 2 minutes more. When the onion turns translucent, stir in the minced garlic and cook just until fragrant, about 30 seconds.
Step 3: Make the Creamy Sauce
Sprinkle the flour over the sprouts and onion and stir constantly for 1 minute to cook out the raw flour taste. Slowly pour in the whole milk and heavy cream while stirring, then add the salt, pepper, and nutmeg.
Bring the mixture to a gentle simmer and cook, stirring often, until it thickens enough to coat the back of a spoon, about 3 to 4 minutes. Take the skillet off the heat before the sauce reduces too much.
Step 4: Assemble the Casserole
Stir half of the crisp bacon and half of the shredded Gruyère into the saucy sprouts until everything is evenly coated. If your skillet is not oven-safe, transfer the mixture to a greased 2-quart baking dish now.
Scatter the remaining cheese across the top, then finish with the fried onions. The sauce should look creamy but not soupy at this point, if it feels too thin let it cool a minute and it will set up.
Step 5: Bake and Serve
Slide the casserole onto the middle rack of the oven and bake uncovered for 20 to 25 minutes. You know it is done when the edges are bubbling hard and the fried onions are deep gold, not burnt.
Pull the skillet out and let the casserole rest for 5 minutes. The sauce will settle slightly, making it easier to spoon generous portions straight onto plates while it is still piping hot.
A Few Notes Before You Start
- Cut through the core: when halving sprouts, slice right through the tiny stem so the leaves hold together while cooking.
- If you do not own an oven-safe skillet, use a regular pan for the stovetop then transfer everything to a greased 2-quart baking dish before Step 4.
- Shred your own cheese: pre-shredded bags have anti-caking agents that keep the sauce from getting as silky.
- The 5-minute rest after baking is not optional. It prevents the casserole from sliding into a puddle when you serve it.
Bake times depend on your dish shape and depth:
| Dish Type | Bake Time at 375°F |
|---|---|
| 2-quart round casserole | 20 to 25 minutes |
| Cast-iron skillet (10-inch) | 20 to 22 minutes |
| Deep 9×13-inch dish | 25 to 30 minutes |
Storing Leftovers
- Refrigerate: keep in an airtight container for up to 3 days. The fried onion topping will soften, but the flavor stays.
- Reheating: warm individual portions in the microwave or bring the whole dish back to life in a 350°F oven for 15 minutes. A quick broil can revive some crispness on top if you have extra fried onions to sprinkle over it.
- Freezing: is not ideal here, the sauce can separate and the topping turns soggy.
What to Serve With Brussels Sprout Casserole
A simple salad with a sharp vinaigrette cuts through the richness of the cream and cheese. Roasted chicken thighs turn this into a heartier dinner. For a carb on the side, buttered egg noodles catch any extra sauce nicely.
Frequently Asked Questions
Can I use frozen Brussels sprouts?
You can, but the texture will be softer. Thaw them fully, pat them very dry, and skip the caramelizing step, just stir them into the sauce.
Can I make the casserole ahead of time?
Yes. Assemble everything through Step 4 without the fried onions on top. Cover and refrigerate up to 24 hours. Add the fried onions right before baking and add 5 to 10 minutes to the bake time.
Is there a substitute for heavy cream?
Half-and-half works, or use 1½ cups whole milk total and skip the cream. The sauce will be a little thinner but still creamy.
Can I use pre-shredded cheese?
A block you grate yourself melts smoother because it has no added starches. Pre-shredded works in a pinch, but stir gently so the sauce does not get gummy.
How do I make this vegetarian?
Leave out the bacon. Cook the onion and sprouts in 2 tablespoons of butter with a pinch of smoked paprika. The dish loses the bacon fat depth, but the cheese and fried onions still carry plenty of flavor.
Cheesy Bacon Brussels Sprout Casserole Recipe
Ingredients
Method
- Preheat oven to 375°F (190°C). Cook diced bacon in an oven-safe skillet over medium heat until crisp, 6-8 minutes. Remove bacon and leave 2 tbsp fat in the pan.
- Add sprouts cut-side down and onion. Cook without moving 3-4 minutes until golden, then stir and cook 2 minutes more. Add garlic and cook 30 seconds.
- Sprinkle flour over the vegetables, stir 1 minute. Slowly pour in milk and cream, add salt, pepper, nutmeg. Simmer until thickened, 3-4 minutes, then remove from heat.
- Stir half the bacon and half the cheese into the sprouts. Top with remaining cheese and fried onions.
- Bake uncovered 20-25 minutes until edges bubble and topping is golden. Let rest 5 minutes, then spoon onto plates and serve hot.
Notes
