01 - Preheat oven to 350°F or set a large skillet or griddle over medium heat.
02 - Using a serrated knife, slice the entire sheet of Hawaiian rolls horizontally in one piece without separating them. Place the bottom half on a baking sheet or clean work surface.
03 - Distribute cheddar and mozzarella slices evenly across the bottom half of the rolls, covering the entire surface. Place the top half of the rolls back over the cheese layer.
04 - In a small bowl, combine softened butter with garlic powder and chopped parsley. Mix until well blended, then spread the mixture evenly over the top of the rolls using a pastry brush or spoon.
05 - For oven method: bake uncovered for 12 to 15 minutes until cheese is fully melted and tops are golden brown. For skillet method: carefully separate into individual rolls and grill each side for 2 to 3 minutes until golden with melted centers.
06 - Remove from heat and allow to cool slightly. Separate into individual mini sandwiches if baked whole, and serve warm.