In a medium-sized bowl, place the butter, parmesan cheese, garlic powder, and Italian seasoning and mix it together until all is combined and smooth.

Spread the butter mixture over one side of the bread slices evenly. Then lay the pieces of bread butter side up onto a sheet tray until you're ready to use them.

Over medium-low heat, in a skillet, place a piece of bread butter side down into the skillet. Then place a slice of mozzarella on top of the bread. Then, add 6 pepperoni slices, followed by another slice of mozzarella cheese, 6 more pepperonis, and a final slice of mozzarella cheese.

Place the top piece of bread on, butter side up. You may end up with leftover pepperoni.

Place a lid on the skillet to help melt the cheese, and cook until the bottom of the bottom piece of bread is a golden brown, typically takes about 3-5 minutes. Carefully flip the sandwich over using a spatula.

Place the lid back on again and continue to cook the other side until it's golden brown on the bottom and the cheese is melted in the center. Repeat with the remaining sandwiches.

Serve immediately with warm pizza sauce for dipping and enjoy.