Grease or oil a 9x13-inch baking pan and set it aside for now.
Cook your pasta according to package directions.
Meanwhile, combine the ground beef, diced onion, bell pepper, salt, and pepper in a skillet. Cook over medium heat until the ground beef is cooked through and the onion and pepper are tender. Drain off any excess grease if necessary.
In a mixing bowl, combine the cooked pasta, ground beef mixture, pizza sauce, Italian seasoning, and olives. Save a few slices of pepperoni and add the rest in. Stir it all to combine.
Spread the mixture in your prepared baking pan.
Sprinkle the parmesan and mozzarella cheeses over the mixture.
Arrange the reserved pepperoni slices on top.
Bake uncovered for 20-25 minutes, or until the mixture is nice and bubbly and are kissed with golden spots around the edges.