Pão de Ló: Portuguese sponge cake
Portugal (multiple regional variants)
Portugal's ancient sponge cake — one of the oldest European sponge preparations, predating the French biscuit de Savoie and the Italian pan di Spagna. Pão de Ló is pure egg: egg yolks, whole eggs, sugar, and flour (or no flour at all in some versions), whisked to a thick ribbon and baked carefully to produce a cake that ranges from fully set (the Alfeizeirão version) to barely set (the Ovar version, which has a deliberately runny centre that oozes when the top is cut).
The Ovar version — pão de ló húmido (wet sponge) — is perhaps the most technically demanding of all Portuguese pastries: it must be baked to a precise point where the exterior is just set but the interior is still a pourable custard.