Heat oven to 350 F. Cook the noodles according to package directions and drain. Brown the ground beef, drain the fat, and stir in the pizza sauce. Spread the noodles in the bottom of a 9-by-13-inch baking dish. Top with the beef mixture, then the cheese, then the pepperoni. Bake 25 to 30 minutes, until the cheese is melted and bubbly.