Cook sausage over medium-high heat until browned and no longer pink, stirring frequently to crumble.
Add flour and whisk; coating all sausage crumbles
Add salt and pepper, stirring to combine
Add milk 1/2 cup at a time, allowing the gravy to thicken in between addition of more milk. Repeat until all 4 cups of milk has been added.
Continue to stir until gravy thickens and is to your preferred consistency.
Serve over warm biscuits