# Method:
01 - Arrange bread slices on a clean surface.
02 - Evenly spread a thin layer of mayonnaise on one side of each bread slice.
03 - If desired, spread a thin layer of Dijon mustard on the opposite side of two bread slices.
04 - Place 2 slices of cheese between two bread slices with mayonnaise-coated sides facing outward. Repeat for the second sandwich.
05 - Heat a nonstick skillet over medium-low heat.
06 - Place sandwiches mayo-side down in the skillet and cook for 3 to 4 minutes until golden brown.
07 - Flip sandwiches and cook for 3 to 4 minutes, pressing gently with a spatula, until bread is golden and cheese is melted.
08 - Remove sandwiches from skillet, let rest for 1 minute, then slice and serve immediately.