Small sandwiches are always a hit on the appetizer table, and these quick and easy tomato-cheese melters are no exception. Another time, make these stacks with large slices of bread (rather than bruschetta) and serve the sandwiches for lunch or dinner.
Preheat oven to 425 degrees F. Line a baking sheet with foil; set aside. In a small bowl, combine butter and garlic. Lightly spread butter mixture on one side of each bread slice. Place a piece of cheese on the buttered side of each of six of the bread slices; top each with a tomato slice, another piece of cheese, and a remaining bread slice, buttered side down.
Pull the leaves off the bottom 2 inches of each rosemary sprig. Push a sprig into each stack to hold it together. Place stacks on the prepared baking sheet.
Bake about 4 minutes or until cheese is starting to melt. Serve warm. If desired, sprinkle lightly with salt and pepper. Cut each stack in half.