In a nonstick or cast iron pan, melt the butter over medium-low heat for about 2 minutes.
Crack the egg in a bowl and carefully transfer it to the pan. Cover the pan with a lid and cook for 2-3 minutes or until the whites are fully set.
Gently slide the spatula under the egg whites all the way around, before sliding it under the yolk to help separate the egg from the pan and reduce the chances of the yolk breaking. Lift it from the pan, and carefully place it on a plate to serve. Season with salt and pepper.