If you think Brussels sprouts are just a side that no one fights over, think again! This Brussels Sprouts Gratin takes tender, caramelized sprouts and smothers them in a rich, creamy cheese sauce with Gruyère and Parmesan, then bakes them until golden and bubbly! The result is a dish that’s both comforting and elegant, perfect for weeknight dinners or as a standout vegetable side dish on your Thanksgiving menu, Christmas menu, or both, especially alongside my popular Cheesy Scalloped Potatoes!
Ingredients & Substitutions
- Brussels Sprouts: Use one pound of fresh Brussels sprouts, trimmed and halved. Choosing firm, bright green sprouts ensures they stay tender but not mushy. If you prefer, you can also use frozen Brussels sprouts; just thaw and pat dry before cooking.
- Butter: Unsalted butter adds richness and depth to the sauce. If you only have salted butter, reduce the added salt slightly.
- Onion & Garlic: A finely diced yellow onion softens beautifully in the butter and provides a subtle sweetness, while minced garlic adds savory depth. For a milder flavor, reduce the garlic to 1 teaspoon.
- Crushed Red Pepper Flakes: Just ½ teaspoon gives a gentle hint of heat without overpowering the dish. You can omit for a completely mild gratin.
- Flour: The flour helps thicken the sauce. All-purpose flour works best, but gluten-free blends can be used if needed.
- Chicken Broth & Heavy Cream: The combination of chicken broth and cream makes the sauce silky and flavorful. For a vegetarian version, use vegetable broth instead of chicken broth.
- Cheese: Gruyère adds a nutty, melty richness, while Parmesan contributes sharp, savory notes. You can swap Gruyère for Fontina or Emmental if desired. For a lighter version, reduce the cheese slightly, but the dish will be less decadent.
- Parsley: Freshly chopped parsley is optional but adds a pop of color and freshness on top before serving.
FAQs
Can I make this gratin ahead of time?
Yes! Assemble the gratin up to the point of baking, cover it, and refrigerate for up to 24 hours. When ready, bake it for a few extra minutes until bubbly and golden.
Can I freeze Brussels Sprouts Gratin?
Absolutely. Cool completely, cover tightly with foil, and freeze for up to 2 months. Thaw overnight in the refrigerator before baking as directed.
Why use Gruyère and Parmesan together?
Gruyère melts beautifully and adds a nutty, creamy richness, while Parmesan provides a sharp, savory bite. The combination gives this gratin depth and a golden, bubbly top.
Can I make it vegetarian?
Yes! Swap the chicken broth for vegetable broth, and the dish is fully vegetarian without sacrificing flavor.
Can I make this without an oven-safe skillet?
Yes! If you don’t have an oven-safe skillet, you can prepare the sauce and toss the Brussels sprouts in a regular pan on the stovetop. Then transfer everything to a greased baking dish before adding the cheese and baking in the oven. Make sure the dish is large enough so the sprouts aren’t overcrowded—this ensures even baking and a bubbly, golden top.
Serving Ideas
- Weeknight dinners: Pair with roasted chicken, pork tenderloin, or simple steak bites for an elevated meal that’s cozy but impressive.
- Vegetarian spread: Serve alongside roasted root vegetables, grain bowls, or a hearty lentil dish for a filling meatless option.
- Potluck or dinner party: This gratin travels well in a covered baking dish and can be reheated at the host’s home for a creamy, crowd-pleasing side.
How To Store Brussels Sprout Gratin
Refrigerator: Store leftovers in an airtight container for up to 3-4 days. Reheat gently in the oven to keep the top golden.
Freezer: Freeze for up to 2 months. Thaw overnight in the refrigerator and bake until warmed through.
Brussels Sprouts Gratin
Ingredients
- 1 pound Brussels sprouts, washed, trimmed, halved
- 2 tablespoons unsalted butter
- 1 small yellow onion, finely diced
- 2 teaspoons garlic, minced
- ½ teaspoon crushed red pepper flakes
- 2 tablespoons all-purpose flour
- ½ cup (120 g) chicken broth
- ½ cup (119 g) heavy whipping cream
- ½ cup (54 g) Gruyère cheese, shredded
- ½ cup (50 g) Parmesan cheese, freshly grated
- ½ teaspoon Kosher salt
- ¼ teaspoon black pepper
- parsley, chopped, for garnish
Instructions
- Preheat oven to 400°F (200°C). Bring a large pot of salted water to a boil. Add the Brussels sprouts and cook until just fork-tender, about 4-5 minutes. Drain and set aside.
- In a large cast-iron (or oven-safe) skillet over medium heat, melt butter. Add onion, and cook until softened, about 3-4 minutes.
- Stir in the garlic and crushed red pepper flakes, stirring for 30 seconds.
- Sprinkle the flour over the onion mixture and stir constantly for 1 minute to create a roux.
- Gradually whisk in the chicken broth. Once the sauce thickens slightly, pour in the heavy cream and whisk until smooth and creamy, about 2-3 minutes.
- Season with salt and pepper.
- Add the cooked Brussels sprouts to the skillet and gently fold them into the sauce, making sure each piece is coated evenly.
- Sprinkle the Gruyère and Parmesan cheese evenly over the top.
- Transfer the skillet to the oven and bake for 15 minutes, or until bubbly and golden brown on top. For a deeper golden finish, broil for 1-2 minutes at the end, watching carefully so it doesn't burn.
- Let the gratin sit for 5 minutes before garnishing with chopped parsley. Serve warm.
Did you make this recipe?
You can tag me at @iamhomesteader.
What the Test Kitchen had to say about this recipe:
Autumn
These are unbelievable! I love the slight kick from the red pepper flakes, and you can't go wrong with lots of cheese!
Elizabeth
These are cheesy in the best way! But, I think I could use a little less, and the Brussels sprouts would still be amazing!
Stephanie
I love Gruyere cheese, so I knew I would love these Brussels sprouts, and I did.
Bella
This is incredible! The cheese sauce coats the Brussels sprouts perfectly. This will be popular at holiday tables, I think.
