Spread 1/2 tbsp of mayonnaise onto each slice of bread, on one side.
Put both cheeses onto two of the bread slices and then put the other bread slices on top of that to form the sandwiches.
Put a pan on the stove over medium heat with half of the butter and cook both sandwiches for 2 minutes.
Turn the sandwiches around, add the rest of the butter and cook for 2 minutes until they are golden brown. Take the sandwiches off the heat and they are ready!