In a mixing bowl, combine 4 tablespoons of softened unsalted butter, 2 tablespoons of grated Parmesan cheese, 1 teaspoon of garlic powder, and 1 teaspoon of dried Italian seasoning. Blend until smooth.

Spread the butter mixture evenly on one side of each of the 4 slices of bread.

Lay one slice of bread in the skillet, butter side down. Layer with 1/2 cup of shredded mozzarella and 1/4 cup of pepperoni. Add another layer of mozzarella and top with a second slice of bread, butter side up.

Cook the sandwich for 3-5 minutes until golden brown and crispy. Flip gently and cook the other side for an additional 3-5 minutes.

Remove from skillet, cool for a minute, slice in half, and serve with warm pizza sauce for dipping.