Icing, often called frosting in the United States, is a sweet, often creamy glaze made of sugar with a liquid, such as water or milk, that is often enriched with ingredients like butter, egg whites, cream cheese, or flavorings. It is used to cover or decorate baked goods, such as cakes or cookies. When it is used between layers of cake, it is called filling.
Icing can be formed into shapes such as flowers and leaves using a pastry bag. Such decorations are commonplace on birthday and wedding cakes. Chef's color dye (food coloring) is commonly added to icing mixtures to achieve the desired color. Sprinkles, coloring mist, edible ink designs, or other decorations are often used on top of icing.
The simplest icing is a glacé icing, containing powdered sugar and water. This can be flavored and colored as desired, for example, by using lemon juice in place of the water. More complicated icings can be made by beating fat into powdered sugar (as in buttercream), by melting fat and sugar together, by using egg whites (as in royal icing), and by adding other ingredients such as glycerin (as in fondant). Some icings can be made from combinations of sugar and cream cheese or sour cream, or by using ground almonds (as in marzipan).
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