With tender roasted Brussels sprouts and a rich, creamy cheese sauce, this Brussels sprouts gratin is a standout side dish for holidays or cozy family dinners. Layered with sautéed leeks, shallots, and garlic, then topped with a crisp buttery breadcrumb crust, it delivers incredible depth of flavor in every bite. Best of all, it comes together easily with simple ingredients, and can be prepped ahead to make entertaining stress-free. Serves at least 8 people.
A Sublime Gratin For The Holidays
I know Brussels sprouts can be polarizing, which is why it always surprises me when this gratin ends up being everyone’s favorite thing on the table every time I serve it. Multiple layers of flavor are built right from the start: leeks, shallots, and garlic are cooked into a creamy roux enriched with two cheeses, while pre-roasting the sprouts ensures they become perfectly tender and full of flavor even before they meet the sauce.
Everything is then finished with a crispy, buttery breadcrumb topping I truly hope you don’t skip—it’s my favorite part. The result is a gratin that’s indulgent yet balanced, and as elegant in appearance as it is wonderful to eat. Served hot and bubbling from the oven is unquestionably the best way to enjoy it, but I’ll also show you how to get most of the work done in advance.
This Brussels sprouts gratin has loads of flavor and has become a staple on our holiday table, especially at Thanksgiving or Christmas alongside favorites like Sage and Sausage Stuffing, Green Bean Casserole, and Honey Maple Roasted Carrots. But it’s also a fantastic side dish any time of year. I hope it’s one you come back to again and again.
Key Ingredient Notes
- Brussels sprouts: This gratin is all about the sweet Brussels sprouts so we use 2 1/2 pounds. Once trimmed and halved, the sprouts are roasted until slightly browned and tender before getting tossed with the creamy sauce.
- Aromatics: While you can get away with using just leeks, or just shallots, I find the two alliums make this gratin extra delicious. Fresh garlic is non-negotiable for the best sharp flavor.
- Cheese: Gruyère cheese is a classic cheese to use in gratins because it has a lovely nutty flavor and melts beautifully. You can also use a sharp cheddar or Jarlsberg, Comté or Emmental. We also use Parmigiano Reggiano for the roux and the breadcrumb topping.
- Heavy cream and chicken stock: To make the sauce, I tested versions with all cream, all milk, half-and-half, and heavy cream with chicken broth. The winning combo, without question, was the cream-and-broth mix. It lightens the sauce just enough to let the Brussels sprouts and aromatics shine through. And if you’re keeping things vegetarian, I include easy swaps that work seamlessly.
- Flour: A bit of flour is needed to thicken the sauce.
- Breadcrumbs: I really like the flavor of homemade breadcrumbs for this gratin but feel free to use panko, if you wish. If you’d like to make your own breadcrumbs, simply toast 3 pieces of sandwich bread, then blend into crumbs in a food processor or blender.
Brussels Sprouts Gratin, Step By Step
Pre-heat the oven to 450°F.
Roast the Brussels. In the baking pan you’ll serve the gratin in, toss the sprouts with olive oil and season with salt and pepper. Roast for 25 minutes, until tender.
Cook the aromatics and make the cream sauce. Saute leeks and shallots until buttery soft, then add the garlic, heavy cream, broth and nutmeg.
Add the cheese. Once the cream sauce has thickened remove from heat and stir in the Gruyère and Parmesan. Stir until cheese is melted, then pour the creamy cheese sauce over the roasted Brussels sprouts.
Top with breadcrumbs and bake. Sprinkle the gratin with the breadcrumbs and parm mixture, then bake uncovered for 18-20 minutes, at 425ºF, until cheese is bubbly and breadcrumbs are golden. Let sit for just a few minutes, then serve.
Make Ahead
You can roast the Brussels sprouts and sauté the aromatics up to 2 days ahead. When ready to make the gratin, add the cooked aromatics to a saucepan, then proceed with making the roux and cheese sauce. (You will likely need to add another tablespoon of butter to the vegetables before adding the flour.)
Alternatively, you can make the recipe all the way up to where you add the cream sauce to the sprouts, then cover and refrigerate up to 1 day ahead. Bring to room temperature before topping with the breadcrumb mixture and baking.
Frequently Asked Questions
Unfortunately, for a rich, luxurious gratin, heavy cream is required. Here it is mixed with chicken broth so using milk would result in a very runny gratin.
Absolutely. Use a vegetable broth that isn’t too strong (homemade would be best) or this vegetarian chicken flavored bouillon.
I love serving this lovely gratin as a Thanksgiving or Christmas side dish, but it’s also a very elegant and fabulous dish to serve alongside roasted meats, fish, or as a part of a vegetarian meal.
Let Me Know Your Thoughts
If you gave this Brussels Sprouts Gratin recipe a try, I would love to hear how it worked out for you. Share your thoughts in the comment section below or feel free to ask me anything — I always enjoy chatting with you.
Don’t forget to leave a star rating, too!~Sandra x
Brussels Sprouts Gratin
Ingredients
- 2 1/2 lbs Brussels sprouts trimmed and halved (discard any yellow leaves)
- 5 tablespoons olive oil, divided
- kosher salt and freshly ground black pepper
- 4 Tablespoons unsalted butter, divided
- 3 medium leeks, white and pale green parts, trimmed, halved lengthwise and coarsely chopped
- 1 large shallot, minced
- 3 garlic cloves, minced
- 2 Tablespoons all-purpose flour
- 1 cup heavy creamy
- 1 1/4 cups low-sodium chicken broth
- 1/8 teaspoon freshly grated nutmeg
- 4 oz freshly grated gruyere cheese
- 1/2 cup freshly grated Parmigiano Reggiano, divided
- 1 cup coarse fresh or dried bread crumbs or panko bread crumbs
Instructions
- Heat oven to 450ºF degrees. In a 13 by 9-inch baking dish, toss Brussels sprouts with 3 tablespoons olive oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper. Bake until sprouts are tender and browned in spots, 25 to 30 minutes. Lower oven heat to 425ºF.
- Meanwhile, melt 2 tablespoons butter and 1 tablespoon olive oil in medium saucepan over medium heat. Add leeks, shallots and garlic and season with 1/2 teaspoon salt and 1/4 teaspoon pepper. Cook, stirring frequently, until they’ve slightly softened, about 5 to 6 minutes.
- Sprinkle flour over the leek mixture and cook, stirring often, for 1-2 minutes (it will seem dry but that's okay). Whisk in cream, broth and nutmeg and bring to a simmer over medium-high heat. Reduce heat to medium and continue to simmer until slightly thickened, about 2 minutes. Remove from heat and add Gruyère, 1/3 cup Parmesan and nutmeg; whisk until smooth. Taste and season with a little more salt and pepper, if needed. Pour cream mixture over Brussels sprouts in baking dish and stir to combine. (At this point, this mixture can be covered and refrigerated up to 1 day ahead. Bring to room temperature before topping with the bread crumb mixture and baking.)
- Melt the remaining 2 tablespoons of butter. In a medium bowl, combine the breadcrumbs, melted butter, remaining 1 tablespoon oil and a pinch of salt and pepper.
- Sprinkle the breadcrumb mixture evenly over the Brussels sprouts. Place the dish back in the oven and bake uncovered for 15 to 18 minutes, or until the cheese is bubbling and the topping is crisp and beautifully golden. Let the gratin rest for just a few minutes before serving.
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