Melt 125 g butter. Coarsely crush 180 g flakes and mix with the butter. Pour the mixture into a greased springform pan (26 cm Ø) and press to a flat bottom. Bake the base in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see
manufacturer) for about 12 minutes.
For the quark mixture, whisk 125 g butter and sugar with the whisks of the hand mixer until foamy. Stir in lemon juice and eggs one after the other. Stir in the quark and starch as well. Sort and puree the blackberries.
Halve the quark mixture. Mix one half with the blackberry puree. Remove the base from the oven. Add the quark and blackberry mixture and continue baking at the same temperature for about 15 minutes. Spread the rest of the quark mixture on top and bake for another 20 minutes.
Remove from the oven and let it cool on a cake rack for about 2 hours. Whip the cream until stiff. Warm up the fruit spread. Remove the cake from the tin, spread the cream on top, sprinkle with fruit spread and sprinkle with the remaining flakes.