Cook pasta according to package directions.
Drain in colander.
Meanwhile, in a Dutch oven, cook beef and onion over medium heat until meat is no longer pink; drain.
Use a hamburger chopper to cut the meat down in small pieces while frying.
Stir in the mushrooms and spaghetti sauce, pizza sauce, granulated sugar and seasonings.
Drain pasta; stir into meat sauce.
Place half of the meat/pasta mixture into greased 10x15" casserole dish.
Sprinkle 2 cups of Mozzarella cheese over sauce mixture.
Layer a 3.5 ounce package of pepperoni slices on top.
Repeat layers once.
Sprinkle Parmesan cheese over top of pepperoni.
Cover casserole with foil or lid and bake about 1 hour at 350° until mixture bubbles on sides.
Remove cover and bake an additional 10 minutes or so until done.