Preheat a skillet or griddle over medium heat.
Spread butter on one side of each slice of bread.
Place two slices of bread, butter-side down, in the skillet.
Spread pizza sauce over the unbuttered sides of the bread.
Top with mozzarella cheese, Parmesan, pepperoni (if using), garlic powder, and oregano.
Place the remaining slices of bread on top, butter-side up.
Cook for 3-4 minutes on each side, pressing gently, until the bread is golden brown and the cheese is melted.
Remove from heat, slice, and serve hot.