Heat a large skillet to medium-high heat. Place 6 slices of bacon in the skillet and cook until almost crispy. Remove the bacon from the skillet and place onto a plate lined with paper towels.
Discard all but 2 tablespoons of the bacon grease from the skillet. Add the flour to the bacon grease and whisk together. Cook for about 1 minute while whisking, being careful not the burn the flour. Add the milk, a little a time, while whisking constantly. Heat until bubbling (about 5-10 minutes), until the sauce starts to thicken.
Meanwhile, crumble the bacon. Add salt and pepper to taste and the crumbled bacon to the gravy. Allow the mixture to simmer until it has reached your desired consistency. Serve over biscuits.