Cut out a butterfly (approx. 8.5 cm Ø) from cardboard as a stencil
Melt the butter. Mix icing sugar and butter with the whisk of the hand mixer, alternately add flour and egg white. Line a baking tray with baking paper. Place a butterfly shape on the baking paper. Put a small tablespoon of dough in the middle of the form and spread the dough evenly thinly. Spread 2-3 more butterflies on the baking tray. Bake in the preheated oven (electric cooker: 150 °C/ convection oven: 125 °C/ gas: see manufacturer) for 12-15 minutes until golden brown
Line a 2nd baking tray with baking paper and spread another 3-4 butterflies on it. Place 2 tall glasses upside down so that a long wooden spoon fits on one glass at each end. Replace the baking trays. Remove hot butterflies from the baking paper immediately with a pallet. Hang the butterflies upside down, centrally between the wings, over the handle of the wooden spoon. Let it cool down. Gradually bake more butterflies until the dough is used up. Store butterfly shanks packed in tins