Amish friendship bread or cake is your basic sweetened
quick-bread. What makes it unique is the cup of starter you add to the
batter, which adds leavening and a bit of sourdough tang to the final bread.
This
starter has (theoretically) been handed down through the generations
from the Amish themselves. If followed exactly, each recipe makes
enough starter for several loaves. You're then supposed to share this
excess starter amongst your friends and thus continue propagating the
recipe.