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.