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 without separating individual rolls. Place the bottom half on a baking sheet or work surface.
03 - Arrange cheddar and mozzarella cheese slices evenly across the bottom half of the rolls, then place the top half of the rolls back on.
04 - In a small bowl, combine softened butter with garlic powder and finely chopped parsley. Evenly spread or brush the mixture over the tops of the rolls.
05 - For oven method: bake uncovered for 12 to 15 minutes until cheese is melted and tops are golden brown. For skillet method: cut into individual rolls and grill each side for 2 to 3 minutes until golden and cheese is fully melted.
06 - Remove from heat, let cool slightly, then separate into individual rolls. Serve warm.