Mix flour, sugar, cocoa, salt and baking powder. Add flavour, egg and fat. Knead everything quickly to a smooth dough. Cover and chill for about 30 minutes. Grease a springform pan (26 cm Ø).
Roll out 1/3 of the dough on the bottom of the mould and enclose the edge of the mould. Halve the remaining dough. Form one half into a roll, place it on the edge and press it up to about 4 cm high. Drain the apricots and lay them on the dough, except for 9 pieces.
Melt the fat and let it cool down. Mix quark, sugar, 1 packet of vanilla sugar, eggs, pudding powder and the cooled fat with the whisk of the hand mixer. Spread the mixture on the apricots until smooth.
Roll out the rest of the dough, tear into pieces and spread on the topping. Bake in the preheated oven (electric cooker: 175 ° C / gas: level 2) for about 1 hour. Take out and let rest for about 10 minutes. Remove from the tin and allow to cool.
Whip cream and remaining vanilla sugar until stiff. Pour into a piping bag with star-shaped spout and squirt tuffs onto the cake. Decorate with remaining apricots, icing sugar and chocolate shavings.