In a large skillet, cook sausage over medium heat until no longer pink, 3-5 minutes, breaking into crumbles. Add butter; heat until melted. Add flour, salt and pepper; cook and stir until blended. Gradually add milk, stirring constantly. Bring to a boil; cook and stir until thickened, about 3 minutes. Remove from heat; cool to room temperature, about 25 minutes., Preheat oven to 400°. On a lightly floured surface, pat or roll each biscuit into a 6-in. circle. Spoon 1/2 cup gravy mixture over half of each circle to within 1/2 in. of edge. Wet edge and fold dough over filling; press edge with a fork to seal., Place on an ungreased baking sheet. Bake until golden brown, 12-14 minutes.