A sweet roll or sweet bun refers to any of a number of sweet, baked, yeast-leavened breakfast or dessert foods. They may contain spices, nuts, candied fruits, etc., and are often glazed or topped with icing. Compared to regular bread dough, sweet roll dough generally has higher levels of sugar, fat, eggs, and yeast. They are often round, and are small enough to comprise a single serving. These differ from pastries, which are made from a paste-like batter; from cakes, which are typically unleavened or chemically leavened; and from doughnuts, which are deep fried.