Heat a non-stick frying pan over medium heat.
Spread butter on one side of each slice of bread.
Place one slice of cheese on one slice of bread (on the unbuttered side), and then top it with the other slice of cheese and the other slice of bread (buttered side up).
Place the sandwich in the preheated pan and cook for 2-3 minutes until the bottom slice of bread is golden brown.
Flip the sandwich over and cook for an additional 2-3 minutes until the other side is golden brown and the cheese is melted.
Take the sandwich out of the pan, cut it in half if desired, and serve hot.