A sheet cake is a cake baked in a large, flat rectangular pan such as a sheet pan or a jelly roll pan. These single-layer cakes are almost always frosted, and may be decorated on the flat surface on the top. In the United States, these inexpensive cakes are commonly available in grocery stores, and are often served at office and birthday parties.
Sheet cakes may be made in any flavor, with chocolate and vanilla being the two most common. They are made from a single piece of cake. Ingredients, such as nuts, chocolate chips, or coconut may be stirred into the cake batter or sprinkled over the top.
If the cake has been split and filled, it becomes a layer cake.