According to the search results, a snickerdoodle is a type of cookie made with flour, fat, sugar, and salt, and rolled in cinnamon sugar. The cookie is characterized by a cracked surface and can be either crisp or soft depending on the ingredients used. The cream of tartar is an essential ingredient that gives the snickerdoodle its unique texture and tangy flavor that sets it apart from other sugar cookies. The flavor of a snickerdoodle is best described as a mix of vanilla and cinnamon with a singular tanginess thanks to the cream of tartar. Some food historians argue that sugar cookie recipes use baking powder to leaven the cookies, while snickerdoodle recipes use cream of tartar. If using cream of tartar, the cookies will have a slightly tangy flavor.