Preheat oven to 350°F.
Cut Hawaiian rolls in half horizontally without separating them into individual rolls.
Place the bottom halves in a baking dish.
Drizzle with balsamic vinegar.
Layer mozzarella slices, basil leaves, and tomato slices.
Season with salt and pepper.
Cover with the top halves of the rolls.
Melt butter and stir in garlic powder, then brush over the tops of the rolls.
Cover with foil and bake for 15 minutes, or until the cheese is melted.
Serve warm and enjoy!