Grease the bottom of a baking tray (approx. 35 x 40 cm). Separate the eggs. Beat the egg white and salt until stiff, adding 125 g sugar and 2 p. vanillin sugar. Beat the egg yolks separately into the mixture. Sift flour, baking powder and 50 g starch into the mixture and fold in. Spread on the baking tray. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/gas: level 3) for about 12 minutes. Cooling down
Peel, quarter and core the apples and cut them into cubes of about 2 cm. Bring juice, 150 g sugar and apples to the boil, cover and simmer for 2-3 minutes (apple pieces should not have fallen apart yet!). Remove the pot from the stove and lift out approx. 1/3 of the apple pieces. Simmer the compote for another 3-4 minutes. Mix 75 g starch and egg liqueur. Stir into the compote, bring to the boil briefly. Stir in the apple pieces again, cool down for about 20 minutes
Cut off an approx. 1 1/2 cm wide edge of the sponge cake all around and crumble finely. Place an adjustable baking tray (or a tray made of aluminium foil folded several times) around the base. Spread the compote on the base. Let it cool down
Mix quark, mascarpone and 100 g sugar. Whip the cream until stiff, adding cream firmer and 1 vanillin sugar. Fold into the mascarpone cream in portions. Spread on the apple layer. Put in a cool place for 2-3 hours. Crumble the meringue. Sprinkle with sponge crumbs on the cake