01 - Lay out all bread slices and spread a thin layer of softened butter on one side of each slice.
02 - Flip two slices buttered side down. Spread 1 tablespoon of marinara sauce evenly across each slice.
03 - Distribute half the mozzarella over the sauced bread. Arrange pepperoni slices atop the cheese, then cover with remaining mozzarella and half the Parmesan.
04 - Place remaining bread slices on top, buttered side facing outward, to complete the sandwich assembly.
05 - Heat non-stick skillet over medium heat. Cook sandwiches 3-4 minutes per side, pressing gently, until bread turns golden brown and cheese melts completely.
06 - Sprinkle oregano, garlic powder, and remaining Parmesan over sandwiches as they complete cooking. Transfer to cutting board.
07 - Slice each sandwich diagonally in half. Serve immediately with warm marinara sauce on the side for dipping.