Flammkuchen is the German pastry traditionally made as a thin, crisp flatbread topped with crème fraîche, onions, and bacon.
The dish originated in the Alsace region and is also associated with neighboring southwestern Germany. Its dough is rolled very thin, spread with a creamy topping, and baked at high heat. The classic topping combines onions and bacon, while modern versions may use ingredients such as cheese, vegetables, or apples.
The name is related to the flames of the traditional oven used to bake it. In German it is called Flammkuchen; the Alsatian name is flammekueche.
Flammkuchen differs from Zwiebelkuchen, which has a thicker yeast-dough base and a softer onion filling. It is also not a conventional sweet fruit pastry, despite the existence of modern dessert versions.