01 - 
                In a bowl, combine shredded chicken, mayonnaise, Dijon mustard, salt, and black pepper. Stir until evenly coated.
              
              
              
                02 - 
                Lay one slice of garlic bread on a surface. Evenly spread the chicken mixture over it. Sprinkle mozzarella and Parmesan cheese on top, then close with the second slice of garlic bread.
              
              
              
                03 - 
                Preheat a non-stick skillet over medium heat. Place the assembled sandwich in the skillet and cook for 4 to 5 minutes or until golden brown. Carefully flip and cook the opposite side until crisp and the cheese is fully melted.
              
              
              
                04 - 
                Remove from the skillet, slice in half if preferred, and serve hot.