01 -
Preheat oven to 400 degrees Fahrenheit.
02 -
Cook bacon in a large cast iron skillet until browned and crisp. Remove bacon with a slotted spoon to a paper towel-lined plate. Reserve 2 to 3 tablespoons of bacon grease and discard the rest.
03 -
Add Brussels sprouts to the reserved bacon grease in the skillet. Season with salt and pepper to taste. Cook over medium-high heat until lightly charred, about 6 minutes. Stir in garlic and cook until fragrant.
04 -
Remove Brussels sprouts to a plate or baking dish if not using an oven-safe pan. Melt butter in the skillet over medium heat and whisk in the flour. Gradually whisk in the heavy cream until heated through. Stir in the parmesan cheese until melted and smooth.
05 -
Return Brussels sprouts and bacon to the skillet and stir to coat. If using a baking dish, pour the cream mixture over the Brussels sprouts and bacon, stirring to coat. Sprinkle the mozzarella cheese and give it a quick stir.
06 -
Bake in the oven for 15 to 20 minutes, or until the center of the dish is bubbly and the Brussels sprouts are tender. Serve immediately.