For the kneading dough: Knead 250 g flour, baking powder, salt, 2 packets of vanillin sugar, sour cream and 175 g soft butter. Cover the dough and chill for about 10 minutes
For the crumbles: 150 g flour, 75 g sugar, 1 packet of vanillin sugar, cinnamon and 100 g cold butter, knead into pieces with your hands
Thirds of a kneaded third. Roll out 1/3 dough on a springform pan (28 cm Ø) and prick several times with a fork. Place the edge of the mould around it. Spread 1/3 crumble on top. Bake in a hot oven (electric cooker: 200 °C/circulating air: 175 °C/gas: level 3) for 15-20 minutes. Remove the base from the mould and allow to cool. Bake 2 more bases from the rest of the dough and crumbles in the same way. Cut 1 base into 12-16 cake pieces immediately after baking. Cool down
Spread the whole 2 bases with plum jam. Whip the cream until stiff, while adding cream firmer, 1 tablespoon sugar and 1 sachet of vanilla sugar. Pour into a piping bag with a large star-shaped spout. Spray 12-16 large cream tuffs onto the edge of 1 base and small tuffs up to the middle. 2. place a cake base on top, spray 12-16 large cream tuffs on the edge and small tuffs to the middle. Place the cake pieces diagonally on the cream tuffs. Chill for about 1 hour.
Dust the cake with icing sugar. Best cut into pieces with a saw knife