A cake recipe for all foodies:
Preheat the oven to 180 °C. For the dough, mix the eggs with the sugar and lemon zest until smooth, then whisk in a hot water bath until creamy, but only until the mixture is lukewarm. Remove the baking bowl from the water bath, then stir the mixture with a hand-held electric mixer for about 5 minutes until well risen, then continue to mix on low speed until cooled. Now fold in the sifted flour.
Grease a ring mold very precisely with butter, dust with flour, pour in the dough mixture and bake on the lowest rack of the oven on the spot, after half an hour turn down the heat to 140°C. The sponge cake is ready when you can poke a wooden skewer into it and pull it out cleanly repeatedly, this usually takes around 50 min.
Then remove the mold from the heat, cool for 10 min. Loosen the edges from the rim of the mold with a kitchen knife, turn the cake out onto a rack, and cool the sponge completely.
For the buttercream, start by mixing the 6 egg yolks with 50 g sugar until creamy. Later, sift the cornstarch over it and mix thoroughly. Boil the milk with the rest of the sugar and the vanilla pod. Later take out the vanilla pod and stir 1/3 of the milk with the egg mixture. Pour everything together one more time back into the saucepan with the milk and cook over medium heat until smooth.