If you are looking for a side dish that perfectly balances creamy, cheesy goodness with the slight bite of roasted vegetables, this Cheesy Brussels Sprouts au Gratin Recipe is an absolute game changer. The tender Brussels sprouts roasted to perfection mingle with a luxuriously creamy Gruyere sauce and tender leeks, creating layers of flavor and texture that make every bite irresistible. Whether you are serving it at a festive holiday dinner or a cozy weeknight meal, this dish brings warmth and richness to the table that will have everyone asking for seconds.

Ingredients You’ll Need

The image shows a white oval baking dish with blue handles on both sides, filled with roasted Brussels sprouts. The Brussels sprouts are halved and whole, bright green with some slightly browned edges, giving a mix of soft and crispy textures throughout. The dish is placed on a white marbled surface, and the Brussels sprouts are spread evenly, covering the entire base of the dish. photo taken with an iphone --ar 4:5 --v 7

This recipe keeps things simple with just a handful of ingredients, each playing a crucial role to ensure the perfect balance of richness, freshness, and that golden cheesy crust. From the earthy Brussels sprouts and mellow leeks to the creamy Gruyere and fragrant herbs, every element shines through beautifully.

1 pound Brussels sprouts, trimmed and halved: Choose fresh, firm sprouts for a tender yet slightly crisp texture after roasting.
1 tablespoon olive oil: Helps the sprouts roast evenly and adds a subtle fruity note.
2 tablespoons butter: The base for your creamy sauce, adding depth and richness.
1 leek, thinly sliced (light green and white parts only): Offers a delicate onion flavor that enhances the sauce without overpowering.
4 cloves garlic, minced: Brings a warm, savory undertone that balances the creaminess.
2 tablespoons flour: Thickens the sauce to a luscious consistency.
1 cup heavy cream: Delivers the silky, indulgent base that wraps around the vegetables.
1 teaspoon Dijon mustard: Adds a sharp, tangy kick to brighten the sauce.
1/2 teaspoon dried thyme: Infuses an earthy, aromatic note to complement the cheese.
1/2 teaspoon rubbed sage: Adds a warm, herbal flavor that pairs beautifully with Brussels sprouts.
4 ounces shredded Gruyere cheese: The star of the dish, melting into a gooey, nutty blanket of flavor.
Kosher salt: Essential for bringing all flavors together.
Fresh cracked pepper: Adds a hint of spice and complexity.

How to Make Cheesy Brussels Sprouts au Gratin Recipe

Step 1: Roast the Brussels Sprouts

Start by preheating your oven to 400 degrees. Toss the halved Brussels sprouts with olive oil, salt, and pepper, making sure every piece gets a light coating. Spread them out in your baking dish and roast for 15 minutes. This roasting step caramelizes the sprouts and develops a rich, slightly nutty flavor that is the perfect base for the creamy sauce.

Step 2: Prepare the Leeks and Garlic

While the sprouts are roasting, melt butter in a large sauté pan over medium heat. Add the thinly sliced leeks along with a pinch of salt and pepper, cooking for 3 to 4 minutes until they soften and start to turn translucent. Then, add the minced garlic for just a minute more, stirring frequently so the garlic becomes aromatic without burning. These ingredients create a delicate flavor backbone for the sauce.

Step 3: Make the Creamy Gruyere Sauce

Sprinkle the flour over the softened leeks and garlic, cooking for about a minute while stirring steadily. This step ensures your sauce thickens properly without any lumps. Gradually pour in the heavy cream, then add Dijon mustard, dried thyme, rubbed sage, and a generous pinch of salt and pepper. Let the sauce warm through for a couple minutes so it slightly thickens.

Step 4: Incorporate the Cheese and Combine

Stir in half of the shredded Gruyere cheese until it melts completely, transforming your sauce into a velvety, cheesy dream. Taste and adjust seasoning if needed. Pour this luscious sauce over the roasted Brussels sprouts in your baking dish, gently tossing to coat everything evenly. Sprinkle the remaining cheese over the top to create that irresistible bubbling crust.

Step 5: Bake to Perfection

Return the dish to the oven and bake for another 15 to 20 minutes. During this time, the cheese topping melts and browns to a golden finish, and the Brussels sprouts become tender yet perfectly cooked. Once done, it’s time to savor every comforting bite!

How to Serve Cheesy Brussels Sprouts au Gratin Recipe

An oval white baking dish with blue handles sits on a white marbled surface, filled with creamy sauce mixed with whole green Brussels sprouts scattered evenly throughout. A layer of shredded pale yellow cheese is spread on top, covering most of the sprouts and sauce underneath. The sauce appears smooth and rich with small black pepper specks visible. The bright green of the Brussels sprouts contrasts with the light creamy white sauce and cheese. photo taken with an iphone --ar 4:5 --v 7

Garnishes

To elevate this dish even further, consider adding a sprinkle of freshly chopped parsley or chives on top just before serving. Not only do these herbs add a pop of color, but they also bring a fresh note that contrasts beautifully with the richness of the cheese sauce.

Side Dishes

This au gratin pairs wonderfully with a roasted meat like herb-crusted beef or garlic chicken. For a vegetarian option, serve alongside a quinoa pilaf or a crisp green salad with vinaigrette to balance the creamy heaviness. It’s a versatile dish that complements a crowd of flavors!

Creative Ways to Present

For special occasions, serve the Cheesy Brussels Sprouts au Gratin Recipe in individual ramekins for a charming personal touch. Alternatively, layer it in a large gratin dish topped with breadcrumbs and pecans for extra crunch. Presentation is as fun as the flavors!

Make Ahead and Storage

Storing Leftovers

If you have leftovers, store them in an airtight container in the refrigerator for up to 3 days. The flavors deepen over time, making the dish even more delicious the next day.

Freezing

This dish freezes well for up to 2 months. Allow it to cool completely, then cover tightly with plastic wrap and foil or transfer to a freezer-safe container. Freeze before baking for best texture upon reheating.

Reheating

Reheat leftovers in a 350-degree oven until warmed through to restore that bubbly, crusty top. Microwaving works for a quick fix but may cause the sauce to become a little watery, so use the oven whenever possible for the best result.

FAQs

Can I use a different cheese instead of Gruyere?

Absolutely! While Gruyere offers a unique nutty flavor and great melting properties, Swiss or fontina work well as substitutes. Just choose cheeses that melt smoothly and have a mild, complementary taste.

How can I make the sauce dairy-free?

Try swapping out heavy cream for full-fat coconut milk or a cashew cream. Use dairy-free butter alternatives and a non-dairy cheese substitute that melts well. The flavor will vary slightly but remain delicious.

What if I can’t find leeks?

If you don’t have leeks, onions are a great stand-in. Use finely sliced yellow or sweet onions and cook them gently to achieve similar sweetness and softness.

Is it possible to prepare this recipe gluten-free?

Yes! Replace the all-purpose flour with a gluten-free alternative like rice flour or cornstarch to thicken the sauce without any gluten.

Can I add bacon or pancetta to this dish?

Definitely. Adding crispy bacon or pancetta before mixing in the cheese sauce will introduce a smoky, savory element that pairs wonderfully with the creamy Brussel sprouts.

Final Thoughts

This Cheesy Brussels Sprouts au Gratin Recipe is one of those satisfyingly cozy dishes that brings comfort and elegance to any table. From the roasted sprouts to the rich Gruyere sauce, every component works together to create a side that feels both special and approachable. So go ahead, give it a try, and get ready to impress your family and friends with this warm, cheesy delight!