Heat oven to 400 degrees. Mix beef, bread crumbs, egg, oregano and salt; press evenly against bottom and side of ungreased pie plate, 9x1 1/4 inches. Sprinkle mushrooms, bell pepper, pepperoni, and olives into meat-lined plate. Pour spaghetti sauce over toppings.

Bake uncovered 25 minutes or until beef is no longer pink in center and juice is clear; carefully drain. Sprinkle with cheese. Bake about 5 minutes longer or until cheese is light brown. Let pie stand 5 minutes before cutting.