Firstly, prepare the batter. Place the eggs, sugar and vanilla sugar in a bowl and beat for 5-10 minutes until frothy. Fold the almonds, cornflour, baking powder and salt into the butter.
Preheat the oven to 170°C (fan-assist). Pour the batter into the greased cake tin and bake for 30-40 minutes. Test with a skewer and leave to cool.
The best variety of apples for the filling is South Tyrolean Gala PGI. While the base is in the oven, dice the apples finely and sprinkle with the lemon juice. Place the apples, sugar, vanilla sugar and juice in a pan, bring to the boil and simmer until the apples are soft (approx. 10 minutes). Blend the cornflour in a little water, add to the simmering apple sauce and stir constantly until the sauce thickens well. Place two tablespoons of the sauce in a bowl and set aside to garnish. If desired, add a little gelatine to the remainder and stir into the sauce while hot for a thicker, firmer result.
Transfer the cooled base to a cake ring or a tall spring-form tin. Spread the apple mixture over the base and chill for approx. 1 hour.
In the meantime, whip the cream, sugar, vanilla sugar and cream stabiliser until stiff. Add the quark and stir in well. Finally, fold in the lemon zest.
Transfer the cream to a piping bag with a star nozzle, decorate the cake as desired and top with your preferred garnish, e.g. chocolate eggs, pieces of apple etc.