In a bowl, combine the flour, salt, garlic powder and pepper; stir in milk and eggs. Pour into a greased 13-in.x9x2 baking pan. In a skillet, cook sausage over medium heat until no longer pink; drain. Sprinkle over the crust. Top with pepperoni, onion, and green pepper.
Bake uncovered, at 425' for 15 minutes or until a toothpick inserted near the center comes out clean. Spread with the pizza sauce and sprinkle with the cheese. Bake 5 minutes longer or until the cheese is melted. Let stand 5 minutes before cutting.