Peel, quarter, core and dice the apples. Sprinkle with lemon juice. Preheat oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer). Grease a rectangular springform pan (approx. 24 x 30 cm). (If you don't have a springform pan, cut a baking tray in half with a multi-folded aluminium foil strip).
Chop the chocolate and melt in a hot water bath with 250 g butter. Beat eggs, sugar, vanilla sugar and 1 pinch of salt for 2-3 minutes until fluffy. Let the chocolate butter shrink while stirring constantly. Mix flour, almonds and baking powder, stir in briefly. Fold in the apple cubes.
Fill the dough into the mould and smooth it down. Bake in a hot oven for about 30 minutes. Let the cake cool down in the tin.
Mix icing sugar with 1⁄4 TL cinnamon, put into a small sieve. Dust the cake with it and cut into squares (approx. 6 x 6 cm).
TIP: White chocolate does not tolerate strong heat and therefore curdles faster than dark chocolate. Therefore, make sure that the water bath does not bubble under any circumstances, but only steam.