For the base, knead flour, sugar, egg, fat in flakes, vanillin sugar and baking powder with the dough hooks of the hand mixer to a smooth dough. If necessary, knead again briefly with cold hands.
Roll out the dough on baking paper to a rectangle (38 x 34 cm). Place on a baking tray (38x34 cm), prick several times with a fork. For the topping, dice marzipan roughly. Knead nuts, marzipan and cognac.
Bring the crème fraîche, sugar and vanillin sugar to the boil in a small pot over medium heat, add to the nut marzipan mixture and mix well. Spread evenly on the rolled out dough.
Bake in the preheated oven (electric oven: 175 °C/ gas: level 2) for approx. 25 minutes on the lower rack. Remove from the oven, place on a rack, let cool for about 10 minutes, cut edges straight so that a plate of about 35x30 cm is formed (edges to try on).
Then cut into 5x5 cm squares, then into triangles. Let it cool down. Coarsely chop the white and dark chocolate coating and melt separately in a warm water bath. Dip half of the nut corners with one corner each into the white couverture, place on a grid and let dry.
Dip the remaining nut corners, each with a corner, into the dark chocolate coating, place on a grid and allow to dry.