Separate the eggs. Beat the egg yolks with sugar and vanilla sugar until frothy (add a little hot water so that the sugar dissolves better). Mix the flour and baking powder and gradually add while stirring. Add the rest of the hot water. Beat the egg whites until stiff and fold carefully into the batter. Line a baking sheet with parchment paper, spread the dough evenly on it and bake for about 30 minutes.
Let the sponge cake cool down and peel off the baking paper. Then coat the bottom generously with the strawberry jam. Whip the cream until stiff and spread it over the jam. Place the shortbreads next to each other on the cream (with my tray, exactly 1 packet of shortbread fits on the cake). Crush the chocolate (I prefer white chocolate) and let it melt in a water bath, then immediately spread it on the shortbread biscuits until they are completely covered.
Decorate with sprinkles or smarties. Chill the cake until the chocolate has set.
Tip: It is best to cut the cake between the biscuits so that the biscuits don`t break (1 biscuit = 1 piece of cake).