Choux pastry, also known as pâte à choux, is a light pastry dough used to make a variety of pastries such as eclairs. It is made from butter, water, flour, and eggs, and is usually piped into small balls or oblong shapes before being baked. The resulting pastry is light and hollow, with a crisp exterior. Éclairs are a popular type of choux pastry, filled with cream and topped with chocolate.