Mash the banana in a bowl with a fork and drizzle with the lemon juice.
Beat the eggs with the sugar and vanilla sugar until frothy. Add the melted butter, flour, yoghurt, desiccated coconut, baking powder, salt, vanilla flavor and mix into a batter. Fold in the mashed banana.
Line a muffin tin with paper liners. Pour in the batter with a tablespoon.
Bake muffins for 20 minutes.
Mix powdered sugar with lemon juice and, if necessary, a dash of water. Before the muffins cool, spread them on them.