Preheat oven to 350 degrees F (175 degrees C). Lightly spray a 9x13-inch baking dish with cooking spray.
Bring a large pot of water to a boil and cook the pasta according to package directions.
While pasta is cooking, cook the sausage in a skillet over medium heat until just lightly pink. Add green bell pepper and onion to the sausage. Continue cooking until the meat is cooked through. Add the pepperoni, olives, cream cheese, and sauce. Cook over low heat until heated through and cheese has melted.
When pasta is done, drain and return to the pot. Stir the sausage mixture into the pasta; stir to coat the pasta.
Add half of the pasta mixture to prepared baking dish. Top with half of the mozzarella cheese. Spread the remaining pasta over the cheese and top with the remaining mozzarella cheese. Sprinkle with the Italian seasoning and place a few pepperoni slices on top, if you like.
Bake until the cheese has melted and the pasta is heated through, about 15 minutes.
