01 - Lay out bread slices on work surface. Spread about 1/2 tablespoon softened butter on one side of each slice.
02 - On unbuttered side of two slices, spread 1 1/2 tablespoons basil pesto evenly across surface.
03 - Layer mozzarella and provolone over pesto, add tomato slices and Parmesan if desired. Season with black pepper.
04 - Top with remaining bread slices, buttered side facing outward to create sealed sandwiches.
05 - Heat large nonstick skillet or griddle over medium-low heat until properly warmed.
06 - Place sandwiches in skillet, cook 3-4 minutes per side while pressing gently until golden brown and cheese melts completely.
07 - Remove from skillet, let rest 1-2 minutes, then slice diagonally and serve warm.