Sprinkle pizza sauce with 3 cups shredded mozzarella cheese (12 oz) and 1/4 cup grated Parmesan cheese.
In 10-inch skillet, cook 1 lb lean (at least 80%) ground beef, 1 cup chopped onion and 1 teaspoon Italian seasoning over medium heat 8 to 10 minutes, stirring occasionally, until beef is thoroughly cooked. Pour into paper towel-lined strainer to drain. Spread beef mixture over pizza sauce. Sprinkle with 2 cups shredded mozzarella cheese (8 oz) and 1/4 cup grated Parmesan cheese.
In 10-inch skillet, cook 1 lb bulk Italian pork sausage and 1 cup chopped green bell pepper (if desired) over medium heat 8 to 10 minutes, stirring occasionally, until pork is no longer pink. Pour into paper towel-lined strainer to drain. Spread sausage mixture over pizza sauce. Sprinkle with 2 cups shredded mozzarella cheese (8 oz) and 1/4 cup grated Parmesan cheese.
Arrange 1 package (3 oz) sliced pepperoni over pizza sauce. Sprinkle with 2 cups shredded mozzarella cheese (8 oz) and 1/4 cup grated Parmesan cheese.
Place the dough from center to the edge to form a 12-inch circle, using floured fingertips. The edge should be slightly thicker than the center to help hold the filling.