Mix flour, icing sugar, vanilla sugar, baking powder and salt in a greased cup. Add grated zest of organic lemon, egg, whole milk yoghurt and oil. Stir well with a fork. Fold in frozen blueberries.
Place cup on a saucer. Cook in the microwave at 800 watts 2-2 1⁄2 minutes. Remove and let rest for 1-2 minutes. Dust with icing sugar.