Cook pasta according to package directions. Meanwhile, in a Dutch oven, cook beef and onion over medium heat until meat is no longer pink; drain. Stir in the mushrooms, tomato sauce, pizza sauce, tomato paste, sugar and seasonings. Drain pasta; stir into meat sauce.
Divide half of the mixture between two greased 11-in. x 7-in. x 2-in. baking dishes; sprinkle each with 1 cup of mozzarella cheese. Repeat layers. Top with pepperoni and parmesan cheese.
Cover and bake at 350°F for 20 minutes. Uncover; bake 10-15 minutes longer or until heated through.