Arrange biscuits about 1 1/2 inches apart on a baking sheet.
Bake in the preheated oven until golden brown, 13 to 17 minutes. Slice cooked biscuits in half crosswise and keep warm.
While biscuits are baking, crumble sausage into a large skillet over medium heat; cook, breaking meat apart, until no longer pink inside, about 10 minutes. Sprinkle sausage and pan drippings with flour and cook and stir until sausage is coated, about 1 more minute. Reduce heat to medium-low.
Pour evaporated milk into sausage mixture, followed by milk; stir until thoroughly combined. Bring to a simmer, stirring constantly, and cook until gravy is your desired thickness, 3 to 5 minutes. Season with salt and ground black pepper. Stir butter into gravy until melted. Stir in more flour if gravy isn't thick enough.
Place biscuits with cut sides up on serving plates; top with sausage gravy.
