 The two most common types are the ring doughnut and the filled doughnut, which is injected with fruit preserves, cream, custard, or other sweet fillings.Alternatively, small pieces of dough are sometimes cooked as "doughnut holes".Once fried, doughnuts may be "glazed" with a sugar icing, spread with icing or chocolate on top, or topped with powdered sugar, cinnamon, sprinkles or fruit.