A sheet cake is a cake

Cake

Cake is a form of bread or bread-like food. In its modern forms, it is typically a sweet and enriched baked dessert. In its oldest forms, cakes were normally fried breads or cheesecakes, and normally had a disk shape...

 baked in a large, flat rectangular pan such as a sheet pan or a jelly roll

Swiss roll

A Swiss roll or jelly roll is a type of sponge cake roll. The thin cake is made of eggs, flour and sugar and baked in a very shallow rectangular baking tray, called a sheet pan. The cake is removed from the pan and spread with jam or buttercream, rolled up, and served in circular slices.The...

 pan. These single-layer cakes are almost always frosted, and may be decorated on the flat surface on the top. In the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, 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

Layer cake

A layer cake is a cake consisting of multiple layers, usually held together by frosting or another type of filling, such as jam or other preserves. Most cake recipes can be made into layer cakes; butter cakes and sponge cakes are common choices...

.