First, eggs, sugar, vanilla sugar and a pinch of salt are whipped until thick and creamy at the highest level for about 20 minutes.
Flour, cornstarch and baking powder are mixed together and sifted into the egg-sugar mass and carefully folded in. Then the melted, not so hot butter is added and also mixed in.
The dough is then filled into a 24 or 26 springform pan lined with baking paper and baked at 175 ° C top and bottom heat in a preheated oven for about 35 - 40 minutes. The oven door must not be opened for the first 25 minutes, otherwise the floor will unfortunately collapse.
After the baking time, to ensure that the sponge cake base does not collapse, you can turn the temperature down completely, clamp a wooden spoon between the oven and the oven door and let it cool down.
Then the sponge cake base is removed from the mold, wrapped with damp kitchen towels and then has to cool down completely. It may only be cut after it has cooled down. It works best when he has rested for a night.