Cook the bacon: In a large skillet or pan, cook the bacon strips over medium heat until they become crispy. After cooking, use a slotted spoon to transfer the bacon to a paper towel-lined plate to absorb excess grease. Set aside. Retain approximately 2 tablespoons of the bacon fat in the pan, discarding any excess.

Sauté the Brussels sprouts: Add the butter to the bacon fat in the same pan and let it melt over medium heat. Add the Brussels sprouts, season with salt and pepper, and sauté for about 5-7 minutes, until they are golden and slightly tender.

Add the garlic: Stir in the finely chopped garlic and cook for another 1-2 minutes until the garlic becomes fragrant.

Create the creamy sauce: Pour the cream into the pan with the Brussels sprouts and stir to combine. Bring the mixture to a simmer. If you prefer a thicker sauce, mix the cornstarch slurry and add it to the pan, stirring continuously until the sauce thickens (about 1-2 minutes).

Add the cheese: Stir in the freshly grated mozzarella and parmesan cheeses until they melt into the cream, creating a smooth, cheesy sauce. Let the mixture simmer for an additional 3-4 minutes, stirring occasionally, until the Brussels sprouts are fully cooked and the sauce has thickened to your liking.

Combine the bacon: Return the crispy bacon to the pan and stir everything together. Sample the dish and modify the seasoning by adding extra salt and pepper as necessary to enhance the flavor.

Serve: Remove from heat and serve immediately, garnished with a little extra parmesan or fresh parsley if desired.