Wash, clean and pat dry the blueberries. Mix flour and baking powder. Whisk the egg. Stir in sugar, vanillin sugar, butter and buttermilk. Stir in flour mixture briefly. Fold in blueberries. Line a muffin tray with 12 trays with 1 paper baking tin each.
Spread the dough inside. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 25 minutes. Let muffins rest for about 5 minutes. Carefully remove from the tray. Let them cool down. Dust with icing sugar. If necessary, put them into colourful paper baking cups
waiting time approx. 1 1/2 hours