Cut the rolls in half. Divide the hummus over the bottom half of each sandwich. Top with one slice of mozzarella cheese, followed by five or six tomatoes. Place a small handful of spinach on top, followed by another slice of mozzarella. Top with the other half of the roll.
Place the sandwiches in the press, working in batches as necessary, and drizzling the tops with a little olive oil before gently pressing down. Cook until the cheese is melted, the bread is toasty, and everything is warmed through, 5-10 minutes. Allow to rest a few minutes before cutting in half and serving.