Knead butter in pieces, icing sugar, 225 g flour, egg yolk and 1 pinch of salt first with the dough hooks of the hand mixer, then with floured hands to a smooth dough. Wrap in foil and chill for about 30 minutes
Knead 100 g dough with 2 tbsp. flour and cinnamon, crumble into crumbles between your hands. Roll out half of the remaining dough between 2 layers of baking paper square (approx. 25 x 25 cm) 4-5 mm thin. Spread half of the plum puree on the dough, cut approx. 14 rhombs (approx. 5 x 13 cm each) out of it with a wavy pastry wheel. Sprinkle half of the crumbles over it, place cookies on a baking tray covered with baking paper. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 15-20 minutes. Remove and let cool on a cake rack. Process remaining dough, plum puree and crumble in the same way
Waiting time approx. 30 minutes