Zwiebelkuchen, which literally means onion cake in the German language, is either a one-crust pie made of steamed onions, diced bacon, cream, and caraway seed on a yeast dough or a leavened dough that's particularly popular in the German winegrowing regions mostly of Rhenish Hesse, the Palatinate, Franconia, and Swabia (A similar pie called Flammkuchen is also eaten in Alsace) or a quiche variant traditionally cooked in the Basel area.… (More on Zwiebelkuchen)