A butter cake is a cake in which one of the main ingredients is butter. Butter cakes consist of taking the most basic of ingredients - butter, sugar, eggs, flour, and a leavening agent (baking powder or baking soda) - and transforming them into a baked good.
These cakes are considered one of the quintessential cakes in American baking. They find their origins in the English pound cake, which traditionally used equal parts of butter, flour, sugar, and eggs to produce a heavy, rich cake.
The invention of baking powder and other chemical leavening agents during the 19th century substantially increased the flexibility of this traditional pound cake by introducing the possibility of creating lighter, fluffier cakes using these traditional combinations of ingredients, and it is this transformation that brought about the modern butter cake.
Butter cakes are traditionally made using a creaming method, in which the butter and sugar are first beaten until fluffy to incorporate air into the butter. Eggs are then added gradually, creating an emulsion, followed by alternating portions of wet and dry ingredients. Butter cakes are often considered[by whom?] to be unsurpassed in their richness and moistness when stored at room temperature, but they tend to stiffen, dry out, and lose flavor when refrigerated, making them unsuitable for filling or frosting in advance with ingredients that must be refrigerated, such as cream cheesefrosting and pastry cream.