According to Wikipedia, by definition, "Choux pastry, or pâte à choux, is a light pastry dough that contains only butter, water, flour and eggs. The high moisture content of the dough causes it to produce steam when cooked, which puffs the pastry." It earned the name "choux" due to its irregular form or shape after baking which resembles that of a cabbage. Choux pastry is used to make profiteroles, éclairs and choux puffs and is the basis of the dramatic dessert Gâteau St Honoré.