Chestnuts are large and wrinkled and have a smooth, shiny, mahogany-colored shell that is slightly flattened on one side. Unlike other nuts, they contain a high amount of starch and little oil. Often treated as a vegetable and almost always cooked, sweet and rich chestnuts are popular simply roasted whole and eaten while still hot. You must cook chestnuts by briefly roasting or boiling them to loosen their tough outer shells and thin, bitter skins. Look for fresh chestnuts that are hard, shiny, unblemished, heavy for their size and do not rattle when shaken. Chestnuts have to be peeled and cooked before using. They can be roasted in their shells, candied, boiled, braised or puréed. They have a sweet nutty flavor. Enjoy them raw, boiled or by roasting. The nuts are used as one of the main ingredients in poultry stuffing, especially in Thanksgiving turkey. Although referred to as a nut because of the hard shell, they have more of a soft, grainy texture inside as opposed to being hard and crunchy like nuts.