Knead 300 g flour, butter in flakes, 100 g sugar, 1 packet vanilla sugar and 1 egg with the dough hooks of the hand mixer to a smooth dough. Wrap in foil and chill for about 30 minutes. In the meantime, whip the cream until stiff and put it in a cool place. Cream 10 eggs, 1 packet of vanilla sugar, 1 pinch of salt and 250 g sugar in a large bowl. Add quark, sour cream, 60 g flour and lemon zest and stir in. Fold in whipped cream.
Put it in a cold place. Boil up the elderberry juice. Mix starch with a little water until smooth and stir into the elderberry juice. Bring to the boil again and simmer for 1 minute. Put it in a cold place. Peel, halve and core apples. Drizzle apples with lemon juice. Roll out short pastry on a floured work surface in a rectangular shape (32 x 39 cm). Line a greased, floured fat pan of the oven (32 x 39 cm) with it. Cover the bottom with some cheese mixture. Place apple halves on top.
Peel, halve and core apples. Drizzle apples with lemon juice. Roll out short pastry on a floured work surface in a rectangular shape (32 x 39 cm). Line a greased, floured fat pan of the oven (32 x 39 cm) with it. Cover the bottom with some cheese mixture. Place apple halves on top. Mix 3 tablespoons of the cheese mixture with the elderberry sauce. Spread the rest of the cheese mixture on the apples and smooth it down. Spread the elderberry mixture drop by drop on the cheese mixture and marble it with a wooden skewer. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 60 minutes. Remove from the oven and let it cool down on a cake rack
Mix 3 tablespoons of the cheese mixture with the elderberry sauce. Spread the rest of the cheese mixture on the apples and smooth it down. Spread the elderberry mixture drop by drop on the cheese mixture and marble it with a wooden skewer. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 60 minutes. Remove from the oven and let it cool down on a cake rack