Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain bacon slices on paper towels and crumble when cool enough to handle.
Add flour to the bacon grease and stir until a paste forms. Cook and stir until lightly browned, about 2 minutes. Gradually add evaporated milk and milk, stirring frequently. Add butter, sugar, pepper, and salt; continue to cook until thickened, about 5 minutes. Stir in crumbled bacon and serve.