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, with decorations and ornamental frosting along the borders and the flat top surface. In the United States, these cakes are commonly available in supermarkets and bakeries and tend to be inexpensive due to their simple manufacturing process. Sheet cakes may be made in any flavor, with chocolate and vanilla being the two most common. Commonly made in the home with boxed cake mixes, they can come in a variety of additional flavors, with colorful batter mix-ins such as sprinkles and chocolate chips. By definition, they are made from a single continuous piece of cake. Ingredients such as nuts, chocolate chips, or coconut may be sprinkled over the top. A layer cake may be made from a sheet cake that has been split, filled with jam or icing, and frosted. A US commercial sheet cake pan is 18x24x2 or 18x26x2 inches in size. In the UK, Canada, and Australia a similar cake is referred to as a slab cake.