Step 1

Preheat your broiler to medium-high heat

Step 2

Place a heavy-bottomed pan over medium heat

Step 3

Add the pancetta and cook, stirring occasionally, until crisp, 3 to 5 minutes

Step 4

Add the onions and garlic and cook until softened, 2 minutes

Step 5

Stir in the thyme and toast briefly

Step 6

Using a slotted spoon, transfer the pancetta mixture to a baking dish and set aside

Step 7

Place the pan back over medium heat and add the Brussels sprouts

Step 8

Season with salt and pepper and cook until beginning to soften, 4 to 5 minutes

Step 9

Using a slotted spoon, transfer the Brussels sprouts to the baking dish containing the pancetta mixture

Step 10

Drain all but 2 tablespoons fat from the pan and whisk in the flour until a smooth paste forms

Step 11

Whisk in the white wine and bring to a simmer, smoothing out any lumps

Step 12

Whisk in the cream and season with nutmeg, salt and pepper, then whisk in the mascarpone

Step 13

Pour the sauce over the Brussels sprouts and mix to thoroughly combine, then smooth the surface

Step 14

In a mixing bowl, stir together the panko, Parmesan and chives and sprinkle evenly over the Brussels sprouts

Step 15

Broil until golden brown on the surface, 3 to 5 minutes