Drain the tangerines.
Grease the muffin tin and set aside to cool. Preheat the oven to 200 degrees (fan 180 degrees, gas mark 3-4).
Beat eggs with sugar and vanilla sugar until creamy, add butter and yogurt and stir until smooth. Sift flour and baking powder on top and fold in.
Fill the cavity of the pan 2/3 of its height with batter. Spread the mandarin orange pieces evenly on top and press lightly into the mixture.
Bake muffins for 20-25 minutes, cool and dust with powdered sugar.