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 individual rolls. Place the bottom half on a baking sheet or cutting board.
03 - Distribute cheddar and mozzarella cheese 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.
05 - Spread the seasoned butter mixture evenly over the top of the rolls using a pastry brush or the back of a spoon.
06 - For oven method: bake uncovered for 12 to 15 minutes until cheese is fully melted and tops are golden brown. For skillet method: cut into individual rolls and grill each side for 2 to 3 minutes until golden with melted cheese.
07 - Remove from heat and allow to cool slightly. Separate into individual mini sandwiches and serve warm.