For the batter, beat the eggs, sugar, vanilla sugar and softened butter until frothy. Mix flour and baking powder, sieve and stir into the mixture. Add lemon juice and salt. Place the dough on a baking sheet lined with baking paper and smooth it out.
Cut the drained peaches into wedges and distribute them evenly on the dough.
For the crumble, cut the cold butter into small pieces, pour sugar, vanilla sugar and sifted flour over it and knead into crumble with your hands. Scatter the streusel over the peaches and bake the cake for 40-45 minutes, then remove from the oven and let cool.
To decorate, roughly chop the chocolate and melt in a water bath. Put the liquid chocolate in a plastic bag, cut off a very small point and cover the cake with a chocolate lattice.