The egg yolks are mixed with the sugar and vanilla sugar until a frothy light yellow. The flour is swirled with the baking soda and then mixed with the egg yolk.

Beat the egg whites with a pinch of salt into a hard foam, then rotate the foam in several portions with gentle, large movements into the flour mixture.

Put baking paper in a large gas baking sheet and cover the dough. Using a rubber spatula, skillfully flatten the top to make it as even as possible.

Place in a preheated oven at 180 ° C and bake in about 15 minutes. Check by needle test.

Cover the finished sponge cake on a clean kitchen towel. Peel a squash, grate it and squeeze the apricot kernel.

The sponge cake is then rolled up relatively tightly and allowed to cool completely in the kitchen towel when rolled up.

Sprinkle the top of the sponge cake roll with powdered sugar and slice it with a knurled knife.