Amish friendship bread is a type of bread or cake made from a sourdough starter that is often shared in a manner similar to a chain letter. The starter is a substitute for baking yeast and can be used to make many kinds of yeast-based breads, shared with friends, or frozen for future use. The sweet, cake-like Amish cinnamon bread is a common bread that is made from this starter; it is a simple, stirred quickbread that includes a substantial amount of sugar and vegetable oil, with a mild cinnamon flavor. It has characteristics of both pound cake and coffee cake. The flavor of the finished product can be altered by cinnamon being omitted.