Cookies

In most cases, cookies are chemically leavened with baking powder or baking soda and have more sugar and fat and less liquid than cakes. During creaming, sugar serves to introduce air into the cookie dough or batter. In general, about half the sugar content of a cookie dough will remain undissolved at the end of the mixing period. As the cookie bakes, the high temperature will melt the fat and cause the dough to become more fluid. The undissolved sugar begins to liquefy as well, and the sugar solution increases in volume, causing the dough to spread. In addition, sugar helps create a golden exterior and wonderful sweet flavor as it caramelizes. In some cookies, such as gingersnaps, sugar assists in the development of a crackled surface.