Prepare the bread: Spread butter on one side of each slice of bread. 

Assemble the sandwich: On the unbuttered side of one slice, spread a layer of pizza sauce. Add a slice of mozzarella cheese on top of the sauce. Sprinkle with pepperoni slices (or your choice of toppings), a pinch of oregano, garlic powder, and grated Parmesan (optional). 

Close the sandwich: Place the other slice of bread on top, with the buttered side facing out. 

Grill the sandwich: Heat a skillet over medium heat. Once hot, place the sandwich in the skillet and grill for 3-4 minutes on each side, until the bread is golden brown and the cheese is melted.