Knead flour, baking powder, 125 g sugar, butter and egg to a smooth dough. Wrap in foil and chill for about 30 minutes. In the meantime wash apples, cut out cores. Cut apples into fine rings and spread them on a fat pan of the oven.
Sprinkle with lemon juice and rum. Finely dice the marzipan. Mix apple rings with 100 g sugar, cinnamon, 50 g almond slivers and marzipan. Cook in the preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for about 20 minutes.
Drain carefully. Fill up to 400 ml with apple juice. Mix pudding powder and 40 g sugar. Add 6 tablespoons apple juice and stir until smooth. Boil up the rest of the apple juice.
Stir in the mixed powder. Leave to boil for 1 minute. Fold in baked apple mixture. Roll out 3/4 of the dough on a floured work surface until round (approx. 28 cm Ø). Put into a greased springform pan (24 cm Ø).
Press the edges of the pastry onto the rim of the springform pan. Sprinkle with breadcrumbs, fill in apple mixture, sprinkle with 50 g almond slivers. Roll out remaining dough, cut out small ornaments and place on the cake and bake in the preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: level 3) for 25-30 minutes.
Take out, let cool and dust with icing sugar. Vanilla ice cream tastes good with it.