Step 1

Heat butter and bacon over medium-high heat in a large straight-sided sauté pan or Dutch oven. Cook, stirring frequently, until well browned, about 8 minutes. Add Brussels sprouts and cook, stirring, until lightly browned, about 4 minutes. Add shallots and cook, stirring, until softened and fragrant, about 1 minute. Add heavy cream and scrape up any browned bits from the bottom of the pan.

Step 2

Adjust heat to maintain a bare simmer. Cook, stirring frequently, until cream has reduced by about half and has a consistency that coats each sprout, about 20 minutes. Season to taste with salt and pepper. Transfer mixture to a casserole pan and cover with shredded cheese (for make-ahead instructions, see note).

Step 3

Adjust oven rack to center position and preheat oven to 425°F. Transfer casserole to oven and bake uncovered until bubbly around the edges and cheese is melted and spotted brown, about 20 minutes. Serve immediately.