2 slices bread
1 slice American cheese
1 slice mozzarella cheese (or enough shredded to cover a slice of bread)
6 pepperoni slices
1 tbsp. mayonnaise
1 tbsp. butter

Spread small amount of mayonnaise on each slice of bread. Add slice of American cheese, then pepperoni to cover, then mozzarella cheese. Top with other slice of bread. Spread butter on bread; grill until cheese is melted.