Separate biscuits; cut each biscuit into forths. Arrange in a greased 13 x 9 inch baking dish (do not flatten). Bake at 375 for 12-15 minutes or until biscuits begin to brown.
Spread spaghetti sauce over biscuit crust. Sprinkle with sausage, mushrooms, peppers and cheeses. Bake for 20-25 minutes or until bubbly and the cheese is melted. Let stand for 5 minutes before cutting.