Heat 2 teaspoons olive oil in a skillet over medium heat. Cook the bread until slightly toasted. Remove from the skillet and rub garlic clove over the toast.
Layer 3 tomato slices, 4 mozzarella slices and 3 basil leaves per sandwich. Drizzle with balsamic vinegar.
Add remaining oil to the skillet and cook sandwich until both sides are golden and cheese is melted. Remove from skillet, drizzle with a little more balsamic and serve immediately.