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 them. Place the bottom half on a baking sheet or clean work surface.
03 - Distribute cheddar and mozzarella cheese slices evenly across the bottom half of the rolls. Place the top half of the rolls back over the cheese layer.
04 - Combine softened butter with garlic powder and finely chopped parsley in a small bowl. Spread the butter mixture evenly over the tops of the assembled rolls using a pastry brush or spoon.
05 - For oven method: bake uncovered for 12–15 minutes until cheese is fully melted and tops are golden brown. For skillet method: cut into individual rolls and grill each side for 2–3 minutes until golden with melted cheese.
06 - Remove from heat, allow to cool slightly, then separate into individual mini sandwiches. Serve warm.