Peel the apple and grate the flesh from the core. Cream the fat, 75 g sugar and vanillin sugar with the whisk of the hand mixer. Separate eggs, stir egg yolks one after the other into the fat mixture.
Mix flour, baking powder and nuts and stir in alternately with the milk. Stir in apple. Pour into a greased springform pan (20 cm Ø) sprinkled with flour.
Pre-bake in the preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: see manufacturer) for approx. 30 minutes. In the meantime, beat the egg whites until stiff, adding 50 g sugar. Spread the meringue on the cake and continue baking for about 15 minutes.
Take out and let it cool down.
Soak gelatine in cold water. Mix mascarpone, apple sauce and 100 g caramel. Dissolve gelatine. Stir in 5 tbsp. of the mascarpone mass, stir into the remaining mascarpone mass. Carefully remove the cake from the mould, cut in half horizontally.
When the mascarpone cream begins to set, spread it on the lower base. Place the upper base on top and chill for about 1 hour. Warm up 2 tablespoons of caramel, if necessary, and decorate the cake with it.