Coarsely crumble the pastry. Separate eggs. Beat the egg whites until stiff, then pour in 100 g sugar. Fold the egg yolks into the beaten egg white. Mix flour, starch and baking powder. Fold flour-mix and biscuits into the egg mixture.
Grease the bottom of a springform pan and dust with flour. Pour in the dough and bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 20 minutes.
Remove from the oven and let it cool down on a cake rack. Peel and quarter the apples and remove the core. Cut quarters into slices. Put apple juice and apple slices in a pot and simmer covered for about 10 minutes until the apple slices are soft but not yet crumbled.
Stir the sauce powder and 3-4 tablespoons of water until smooth, thicken the compote with it. Simmer for about 1 minute while stirring.
Cut off the upper third of the sponge cake and pluck into small pieces. Place a cake ring around the sponge cake and sprinkle the base with coffee. Spread the compote on top and chill for about 1 hour.
Put the sponge cake crumbles on a baking tray lined with baking paper, sieve icing sugar over them. Caramelise lightly in a preheated oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: see manufacturer) for approx. 5 minutes and roast until golden brown.
Remove breadcrumbs from the oven and let them cool down.
Soak gelatine in cold water. Mix mascarpone, 100 g sugar, liqueur and vanillin sugar. Dissolve squeezed gelatine in a small pot. Stir in 3 tablespoons of cream, then stir into the remaining cream.
Chill the cream for about 15 minutes until it begins to gel.
Whip the cream until stiff and fold into the cream. Spread the cream over the apple compote. Put the crumbs on top, press down a little. Chill the cake for about 4 hours. Dust with a little icing sugar before serving.