Only eggs are necessary to make scrambled eggs, but salt is often used, and other ingredients such as water, milk, butter, chives, cream or in some cases crème fraîche, sour cream, or grated cheese may be added. Ground black pepper is sometimes used as an ingredient. The eggs are cracked into a bowl with some salt and pepper, and the mixture is stirred or whisked: alternatively, the eggs are cracked directly into a hot pan or skillet, and the whites and yolks stirred together as they cook. More consistent and far quicker results are obtained if a small amount of thickener such as cornstarch, potato starch, or flour is added; this enables much quicker cooking with reduced risk of overcooking, even when less butter is used. Adding milk or water thins out the mixture, lessens the flavor, and causes the eggs to dry out faster when put over heat because it can separate the egg.
The mixture can be poured into a hot pan containing melted butter or oil, where it starts coagulating. The heat is turned down and the eggs are stirred as they cook. This creates small, soft curds of egg. Unlike pancake or omelette, scrambled egg is virtually never browned. A thin pan is preferable to prevent browning. With continuous stirring, and not allowing the eggs to stick to the pan, the eggs themselves will maintain the pan temperature at about the boiling point of water, until they coagulate.
Once the liquid has mostly set, additional ingredients such as ham, herbs, cheese or cream may be folded in over low heat until incorporated. The eggs are usually slightly undercooked when removed from heat, since the eggs will continue to set. If any liquid is seeping from the eggs (syneresis), this is a sign of undercooking, overcooking or adding undercooked high-moisture vegetables.
Scrambled eggs can be cooked in a microwave oven, and can also be prepared using sous-vide cooking, which gives the traditional smooth creamy texture and requires only occasionally mixing during cooking. Another technique for cooking creamy scrambled eggs is to pipe steam into eggs with butter via a steam wand (as found on an espresso machine).