Knead butter, crème fraîche, flour, baking powder, sugar and salt with the dough hooks of the hand mixer to a smooth dough. Wrap in foil and chill for 1 hour.
Line 2 baking trays with baking paper. Cut off some of the dough with a tablespoon and place 20 - 22 small heaps on each baking tray. Place the baking trays one after the other in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) and bake the cookies for 20-25 minutes.
Dust the cookies thickly with icing sugar and let them cool on a cake rack. Tastes best fresh. Otherwise keep well sealed in tins and sprinkle with icing sugar again shortly before serving