01 - Place a large skillet or grill pan over medium heat and allow it to warm through.
02 - Spread softened butter evenly on one side of each bread slice.
03 - Place two bread slices butter-side down on a cutting board. Arrange one slice each of cheddar, mozzarella, and Gruyère on top of each bread slice.
04 - Drizzle 1 tablespoon of honey over the cheese layers on each sandwich.
05 - Top each sandwich with the remaining bread slices, butter-side facing up.
06 - Transfer sandwiches to the preheated skillet. Cook for 3 to 4 minutes on each side, pressing gently with a spatula, until bread turns golden brown and cheese melts completely.
07 - Remove from pan, cut each sandwich in half diagonally, and drizzle with additional honey if desired. Serve immediately while hot.