1. Heat oven to 350°F.
2. Butter both sides of bread slices. Place on baking sheet.
3. Sprinkle tops with Parmesan cheese and Mozzarella cheese.
4. If freezing, slide sandwich halves into baggies, remove air, and freeze.
5. To bake, place in oven till cheese melts, approx 5-7 minutes (longer if frozen).
6. Cut sandwich halves in half and serve with pizza sauce and pepperoni slices for dipping.