Puff pastry is a flaky light and airy pastry. It contains several layers of dough and fat. The most common fat types are butter and margarine. During baking an open structure is created because the fat melts and the water is turned into steam. This gives the open, airy and crispy structure that puff pastry is known for. Puff pastry is a good method for both a daily fresh product and long shelf life products; for example long shelf life cookies.