The best way to trim the brussels sprouts is to slice of 1/4-inch from the bottom stem end with a paring knife. This will make it easier to peel off any outer tough leaves. Then when cutting the brussels sprouts in half, place them cut-side down on the cutting board to help stabilize them.
You can easily make this dish vegetarian by leaving out the pancetta in step 2. Just add an additional tablespoon of butter in step 3.
- 2 pounds brussels sprouts, trimmed of outer leaves and sliced in half
- 2 ounces pancetta, diced
- 1 Tbsp butter
- 3 shallots, peeled, halved, and sliced
- 2 Tbsp all purpose flour
- 1 3/4 cup whole milk
- Scant pinch of freshly ground nutmeg
- Thyme leaves from 2 sprigs of thyme or 1/2 teaspoon dry thyme
- 4 ounces of grated Gruyere cheese, divided 3 ounces and 1 ounce
1 Blanch the brussels sprouts: Heat a large pot of salted water, 4 quarts of water, 1 Tbsp salt. Blanch the halved brussels sprouts for 3 to 4 minutes, until just barely tender. Remove from pot, drain, rinse with cold water to stop the cooking, set aside.
2 Brown the pancetta and render the fat: Place diced pancetta in a large pot on medium low heat. Cook until most of the fat is rendered, about 8 to 10 minutes. Remove the pancetta from the pan, set aside, leaving the rendered fat in the pan.
3 Sauté shallots, make roux: Add butter to the pot and melt on medium heat. Add the shallots and gently cook until softened, about 4 to 5 minutes. Add the flour to the butter shallot mixture to make a roux, whisk for 1 to 2 minutes.
Add the milk and stir with a wooden spoon until the roux is incorporated into the milk.
Cook over medium low heat for several minutes, stirring, until the sauce thickens and coats the back of your spoon. Add fresh thyme and sprinkle with nutmeg.
4 Add cheese, then half of the pancetta to white sauce: Add 3 ounces of grated Gruyere cheese into the white sauce and stir until the cheese is melted and incorporated into the sauce. Add half of the cooked pancetta back to the sauce. Taste and add more salt if necessary.
5 Add brussels sprouts, transfer to gratin dish, sprinkle with pancetta, more cheese, bake: Preheat oven to 400°F. Butter an 8"x12" gratin dish or casserole . Add the brussels sprouts into the cheese sauce. Transfer the cheesy brussels sprouts into the casserole or gratin dish. Sprinkle with the remaining pancetta and the remaining 1 ounce of grated Gruyere cheese.
Bake for 25 minutes until top is lightly browned and bubbly. Remove from oven and let sit for 10 minutes before serving.