01 - 
                Generously spread softened butter on one side of each bread slice, ensuring even coverage for a golden crust.
              
              
              
                02 - 
                On the opposite, unbuttered side of two bread slices, spread half of the basil pesto. Repeat this for the remaining two slices.
              
              
              
                03 - 
                Evenly layer two slices of mozzarella cheese followed by two slices of sharp cheddar cheese on the pesto-coated side of two bread slices. Top with the remaining two bread slices, ensuring the buttered side faces outwards.
              
              
              
                04 - 
                Heat a nonstick skillet or griddle over medium heat. Carefully place the assembled sandwiches in the hot skillet. Cook for 3 to 4 minutes per side, or until the bread is perfectly golden brown and the cheeses are thoroughly melted and bubbling.
              
              
              
                05 - 
                Remove the grilled sandwiches from the skillet and allow them to rest for 1-2 minutes. This brief resting period helps the cheese set. Slice each sandwich diagonally and serve immediately, either on its own or alongside a warm bowl of tomato soup.