After the time has elapsed, remove the baking sheet from the oven, cover the cake with a clean towel and gently turn it over. We get the cake with the filling on top. Using a towel, twist the roll and leave it to cool.
Put the apple filling on a baking sheet covered with baking paper. Using a spatula, distribute all the filling evenly. Sprinkle with cinnamon and seeds / nuts on top. Put the dough on the filling and distribute it evenly. We send the baking sheet into an oven preheated to 190 ° C and bake for 20 minutes (we watch our oven).
In a bowl, beat eggs, sugar, a pinch of salt, baking powder and vanilla sugar. Beat until the mass turns white and thickens, about 7-10 minutes. Then, sift the flour and stir in the flour with gentle movements. The biscuit dough is ready.