1. Preheat oven to 375°F.

2. Cook the pasta according to package instructions until al dente. Drain and set aside.

3. In a large mixing bowl, combine the cooked pasta, spaghetti sauce, 3 cups of mozzarella cheese, chopped pepperoni, and dried oregano. Mix well.

4. Transfer the mixture to a greased 9×13 baking dish. Top with the remaining 1 cup of mozzarella cheese and a few extra pepperoni slices.

5. Bake for 25-30 minutes, or until the cheese is melted and bubbly.

6. Serve hot, garnished with grated parmesan cheese.