In a small bowl, mix butter with Italian seasoning and garlic powder. Spread the seasoned butter on one side of each bread slice.
On the unbuttered side of 4 bread slices, spread 2-3 tablespoons of pizza sauce evenly.
Layer with mozzarella cheese, pepperoni slices, and any optional toppings you'd like.
Top with remaining bread slices, buttered side facing up.
Heat a large skillet over medium-low heat. Place sandwiches in the pan, buttered side down.
Cook for 4-5 minutes until golden and crispy, then flip carefully. Cook another 4-5 minutes until cheese is fully melted and bread is crispy.
Let cool for 1 minute, slice, and serve with extra pizza sauce for dipping. Pizza night just got a whole lot easier!