A pastry-style flan is a low, flat dessert. It can have as its base either short crust pastry, or a flat, shallow sponge cake.
The short crust pastry style is popular in England. The crust will often, though not always, be blind baked first. This style is more like a low, flat pie with no top crust.
The flat sponge cake base style flan is particularly made in northern Europe, particularly in Germany. This is more like a sponge cake with a fruit topping.
The base is a shallow sponge cake baked in a round cake pan. The bottom of this pan is raised in the centre, causing the cake when turned out of the pan to have a plateau in the middle with raised edges around it. The pans used to make the cakes in are referred to in English as “flan pans.”
You can also buy these flan bottoms ready-made in many grocery stores. Sometimes they may be referred to as “cake bottoms”, with the “flan” being the final product that you make with the cake bottom as your base. In German, they are known as Tortenboden — cake bottoms.
Whether the base is pastry or cake, a custard is typically spread on top of this, then it is topped with fruit. Germany-style flans usually have the fruit then glazed as a finishing touch.