Cook the pasta as it directs on the package. Pour cooked pasta into a large bowl. Then add red and green peppers, cucumber, sliced olives, tomatoes, mushrooms, pepperoni, cheese cubes, and onion.
Pour Italian dressing on salad (you can use fat-free or low-fat if you want). Mix well. Put salad in fridge for a couple of hours before serving. Stir again before serving. Sprinkle grated Parmesan cheese on top.