Brussels Sprouts Gratin with Bacon and Gruyère for Thanksgiving

Brussels Sprouts Gratin With Bacon and Cheese for Thanksgiving

This Brussels sprouts gratin combines browned sprouts, a creamy Gruyère sauce, crisp bacon, and a buttery breadcrumb topping. Roasting the sprouts before baking gives them a head start and helps keep the casserole from turning watery. The dish is rich enough for a holiday table, yet the sprouts retain their flavor beneath the cheese.

The recipe serves eight as a side dish. You can prepare the components ahead, then assemble and bake the gratin on Thanksgiving while the turkey rests.

Brussels Sprouts Gratin Recipe

Yield: 8 side-dish servings
Prep time: 25 minutes
Cook time: 45 minutes
Total time: About 1 hour 10 minutes
Oven temperature: 425°F (220°C) for roasting, then 400°F (200°C) for baking

Ingredients

• 2 pounds (900 g) Brussels sprouts, trimmed and halved
• 1 tablespoon olive oil
• 6 ounces (170 g) bacon, cut into small pieces
• 3 tablespoons unsalted butter, divided
• 2 garlic cloves, minced
• 2 tablespoons all-purpose flour
• 1¼ cups (300 ml) whole milk
• ½ cup (120 ml) heavy cream
• 1 teaspoon Dijon mustard
• 1½ cups (about 170 g) shredded Gruyère cheese
• ½ cup (about 45 g) finely grated Parmesan cheese, divided
• ¾ cup (about 45 g) panko breadcrumbs
• ½ teaspoon kosher salt, plus more for the sprouts
• ¼ teaspoon black pepper
• Pinch of freshly grated nutmeg, optional

Instructions

1. Roast the sprouts. Heat the oven to 425°F (220°C). Toss the Brussels sprouts with the olive oil and a generous pinch of salt. Arrange them cut side down on a rimmed baking sheet. Roast for 20 to 25 minutes, until browned in spots and nearly tender. They will finish cooking in the gratin.

2. Cook the bacon. While the sprouts roast, cook the bacon in a large skillet over medium heat until crisp. Transfer it to a paper towel-lined plate. Pour off most of the fat, leaving a thin coating in the pan, or discard it and use a clean saucepan for the cheese sauce.

3. Make the sauce. Reduce the oven temperature to 400°F (200°C). Melt 2 tablespoons of butter in a saucepan over medium heat. Add the garlic and cook for about 30 seconds, just until fragrant. Stir in the flour and cook for 1 minute, stirring often. Gradually whisk in the milk and cream. Simmer, whisking, for 3 to 5 minutes, until the sauce thickens enough to coat a spoon.

4. Add the cheese. Remove the saucepan from the heat. Stir in the Dijon, black pepper, nutmeg if using, Gruyère, and ¼ cup of the Parmesan. Stir until the cheese melts into the sauce. Taste and add salt as needed; the bacon and cheeses are already salty.

5. Assemble the gratin. Put the roasted sprouts and bacon in a 9-by-13-inch baking dish. Pour the cheese sauce over them and fold gently to coat. Scatter the remaining Parmesan over the top.

6. Add the topping and bake. Melt the remaining tablespoon of butter and mix it with the panko. Sprinkle the crumbs evenly over the casserole. Bake at 400°F for 15 to 20 minutes, until the sauce bubbles around the edges and the topping is golden. Let the dish stand for about 5 minutes before serving.

Why Roast the Brussels Sprouts First?

Raw sprouts release moisture as they cook. In a casserole, that moisture can thin the sauce and leave the vegetables steamed rather than tender with browned edges. Roasting first drives off some of the surface moisture and adds a roasted flavor that balances the cream and cheese.

The sprouts do not need to be fully tender before they go into the baking dish. Aim for browned edges and a little resistance when pierced with a knife. If they are already very soft, the second bake may make them mushy.

Cutting the sprouts in half helps them cook evenly. If you have a mix of very large and small sprouts, quarter the largest ones so the pieces finish at roughly the same time. Trim away dry stem ends and remove any loose or damaged outer leaves.

Choosing Cheese and Breadcrumbs

Gruyère melts smoothly and has a nutty, savory flavor that suits a creamy vegetable gratin. Parmesan adds a sharper, saltier note. Together, they make a flavorful sauce without requiring a long list of seasonings.

For the best texture, shred Gruyère from a block. Pre-shredded cheese often contains anti-caking ingredients that can make a sauce less smooth. If Gruyère is unavailable, use an equal amount of Swiss cheese or Fontina. The result will taste different, but both melt well. A little Parmesan can still supply a firmer, saltier accent.

Panko makes a light, crisp breadcrumb topping. Plain dried breadcrumbs also work, though the topping may be denser. Mixing the crumbs with melted butter helps them brown and keeps them from tasting dry. Add them just before baking if you are preparing the casserole ahead.

Making the Gratin Ahead for Thanksgiving

For easier holiday cooking, prepare the parts separately up to a day in advance:

• Roast the sprouts, cool them, and refrigerate in a covered container.
• Cook the bacon and refrigerate it separately.
• Make the cheese sauce, cool it, and store it in a sealed container.
• Measure the panko and Parmesan, but keep the crumbs dry until baking.

The sauce will thicken in the refrigerator. Warm it gently in a saucepan, stirring in a splash of milk if needed, before combining it with the sprouts and bacon. Add the topping only when the casserole is ready for the oven.

You can also assemble the casserole without the breadcrumb topping, cover it, and refrigerate it for up to 24 hours. Since a cold dish takes longer to heat through, allow extra oven time. Bake until the center is hot and the sauce bubbles, then check that the center reaches 165°F (74°C). If the top browns before the middle is hot, cover the dish loosely with foil and continue baking. Add the buttered crumbs during the last 20 minutes so they stay crisp.

Do not leave the assembled casserole at room temperature for more than two hours. Refrigerate leftovers promptly in a covered container and use them within three to four days. Reheat individual portions or the full dish until hot throughout.

Adjusting the Dish to Your Menu

This Thanksgiving Brussels sprouts casserole is substantial, so it pairs well with simply prepared dishes such as roast turkey, mashed potatoes, or a tart cranberry relish. If the rest of the meal is especially rich, you can lighten the gratin by replacing some of the heavy cream with additional whole milk. The sauce will be a little less rich, but it should still coat the sprouts.

For a stronger bacon flavor, reserve a spoonful of the cooked bacon and scatter it over the breadcrumb topping before baking. For a more pronounced cheese crust, add a little extra Parmesan to the panko. Avoid adding too much cheese to the sauce, though; an overly thick layer can make the dish heavy and mask the sprouts.

The gratin is ready when the crumbs are golden and the sauce bubbles at the edges. A short rest after baking gives the sauce time to settle, making it easier to serve neat portions. Serve it warm, while the topping is still crisp.

A Practical Holiday Side

Roasting the sprouts before they meet the sauce keeps this creamy vegetable gratin from becoming watery, while Gruyère, Parmesan, and bacon give it enough savory depth for a Thanksgiving table. Prepare the components in advance if oven space and timing are tight, then add the crisp breadcrumb topping just before baking. The finished dish brings together the comfort of a casserole and the browned, distinct flavor of baked Brussels sprouts.