1 lg. onion, chopped
1 green pepper, chopped
1 lb. ground beef
1 (3 oz.) pkg. sliced pepperoni, chopped
1 (32 oz.) jar commercial spaghetti sauce
1 (12 oz.) pkg. spaghetti
1 c. (4 oz.) shredded Mozzarella cheese
1 tbsp. grated Parmesan cheese

Combine onion, green pepper, ground beef, and pepperoni in a large skillet. Cook over medium heat until beef browns, stirring to crumble. Remove from heat; drain. Return to skillet. Add spaghetti sauce and bring to a boil. Cover; reduce heat and simmer 20 minutes, stirring occasionally. Cook spaghetti according to package directions, omitting salt. Drain. Arrange spaghetti on an oven-proof platter; spoon meat sauce on top. Sprinkle Mozzarella cheese over sauce. Bake at 400 degrees for 3 to 5 minutes. Remove from oven; top with Parmesan cheese. Serve immediately.