Separate eggs. Cream egg yolk and oil. Stir in 100 g icing sugar, vanillin sugar, salt and yoghurt. Beat the egg whites until stiff, while pouring in 50 g icing sugar. Mix flour and baking powder.
Alternately fold egg white and flour into the yoghurt mixture. Line 1 muffin tin (12 wells) with paper cups. Fill in half of the dough. Place 2 chocolate chips in each muffin and spread the remaining dough evenly on top. Bake the muffins in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 20 minutes. Remove from the oven and let them cool down on a cake rack. Sort the raspberries. Stir 250 g icing sugar and egg white until smooth. If necessary, stir in 1 tablespoon of water.
Bake the muffins in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 20 minutes. Remove from the oven and let them cool down on a cake rack. Sort the raspberries. Stir 250 g icing sugar and egg white until smooth. If necessary, stir in 1 tablespoon of water. Spread the icing and raspberries over the muffins