Zwiebelkuchen is the German word which literallly means "onion cake" . It is actually a savory cake made of sauteed onions, cream, eggs and bacon on a rich yeast dough crust. It is a kind of savory Blechkuchen. Zwiebelkuchen is very popular in Germany's wine regions during Autumn.
It is also popular in other German, speaking countries like Austria and Switzerland and even in a region in France near the border of Germany. In Bern, Switzerland, it is called Zibelechueche, while it is called Zwiebelwähe (Zwiebelwaehe) (onion tart) in Basel , Switzerland.
Zwiebelkuchen is also known in English as Onion Cake, Onion Tart, Onion Pie or Onion Quiche