01 - Arrange bread slices on a clean surface. Evenly apply softened butter to one side of each slice.
02 - Invert the bread slices so the unbuttered sides are facing upwards. Distribute 1 tablespoon of pizza sauce uniformly across four of the slices.
03 - On each sauced slice, layer 1/2 cup of mozzarella cheese. Add 6 slices of pepperoni and any desired optional toppings. Sprinkle with dried oregano.
04 - Place the remaining buttered bread slices on top of the prepared halves, ensuring the buttered side faces outwards.
05 - Place a large skillet or griddle over medium heat and allow it to preheat.
06 - Carefully place the assembled sandwiches onto the preheated skillet, buttered side down. Cook for 3 to 4 minutes per side, or until the bread is golden brown and the cheese is thoroughly melted.
07 - Remove the sandwiches from the skillet. Allow them to cool for 1 minute before slicing and serving hot.