Coat a nonstick skillet with cooking spray. Heat the skillet over medium. Add ½ tsp. butter per egg to the skillet. Carefully crack the eggs into the skillet when the butter melts, taking care not to crowd the eggs.
or the most control, fry just 2 or 3 eggs at a time in an 8- to 10-inch skillet. Avoid filling a larger pan with lots of eggs.
Cook the eggs until the white is opaque and set, about 5 min. Run a flexible rubber spatula around the edges of the white and gently swirl the pan to prevent the eggs from sticking. A sunny-side up egg has a very runny yolk and the whites are just set.
Lower the heat if you see the egg white developing brown edges or patches—browning causes the white to taste strong and turns it tough.
Flip the eggs with a large spatula. Cook for 1 min. The yolks will be less runny than sunny-side up eggs and will have slightly firmer whites.
Flip the eggs back over and cook 1 to 2 min. longer. Over-medium eggs will have yolks that are thoroughly set but still slightly soft. The yolk of an over-hard egg does not run at all.
Start by cooking sunny-side up eggs. Add 1 tsp. water per egg to the pan once the whites are just set. Cover the pan with a lid and cook the eggs until the whites are set and the yolks are cooked to your liking, 2 min. for slightly runny; 4 min. for medium-hard.