Mix the milk, oil and egg in a bowl. Sift the flour and baking powder in another bowl. Add also the sugar, vanilla sugar and salt. Stir the milk-oil mixture shortly through the flour. Also add the blueberries in, stir shortly.
Cover the muffin tin with paper cake cases. Divide the batter across baking forms. Bake blueberry muffins 20-25 minutes in a preheated oven (200 degrees). Prick after about 15 minutes a needle in a muffin, if it comes out dry, the blueberry muffins are cooked.
Let the muffins cool the first ten minutes after baking in the muffin tin, then you can let them cool on the grid. Decorate the muffins with icing sugar and blueberries.