Preheat oven to 350°F. Sliced a round of bread lengthwise and then crosswise with a serrated knife, to about ¼ inch from the bottom of the round.
Cut mozzarella cheese slices into small pieces and stuff in between the cuts of the bread.
Mix together the pesto, sour cream, and garlic salt and cook for 30 seconds in the microwave. Stir and cook for another 30 seconds. Take out of the microwave and drizzle (or brush) into each side of the cuts of bread.
Wrap bread round in foil and bake for 30 minutes, then open foil and bake for another 5 minutes or until cheese is melted. Remove from oven and serve immediately, topped with fresh garden tomatoes and chopped basil.
Drizzle with balsamic glaze right before serving. Serve with plenty of napkins!