Cook bacon until crisp
Pour bacon grease into a heat-safe container
Leave about 2 to 4 tablespoons of grease in the skillet
Keep the skillet over medium heat
Add 2 to 4 tablespoons of flour to the grease
Whisk constantly until smooth
Cook the flour and grease mixture for 1 to 2 minutes
Slowly pour in 1 to 2 cups of milk, broth, or a mix of both
Whisk continuously to prevent lumps
Cook until the gravy thickens
Add salt and black pepper to taste
Stir until fully combined
Serve warm