Step 1

Cut the bread in half horizontally. Hollow out and remove most of the soft interior of the bread from each half and save for another use, like DIY breadcrumbs.

Step 2

Spread the cut sides of the bread with the pesto. Layer half of the mozzarella, half of the tomato, and half of the basil inside the bread bottom. Repeat with the remaining mozzarella, tomato, and basil. Place the top on the sandwich, tightly wrap the sandwich in 2 layers of plastic wrap, then refrigerate for at least 1 hour or up to 1 day.

Step 3

If you prefer a warm sandwich, arrange a rack in the middle of the oven and heat to 350°F. Wrap the sandwich with aluminum foil, place on a baking sheet, and bake just until the cheese is melted, about 15 minutes. Cut the sandwich into wedges and serve immediately.