Brown ground beef and onion. Drain. Add salt and pepper to taste. Mix together; add pizza sauce, tomato paste, tomato sauce, sugar and garlic salt. Put 1/2 in 13x 9 casserole dish, cooked macaroni, meat sauce and mozzarella cheese. Repeat; sprinkle with parmesan cheese and top with slices of pepperoni. Bake at 350 for 45 minutes.