Beat the butter until smooth. Add the sugar and vanilla sugar and stir to a smooth mass. Mix in the eggs one by one, then add the cream and limoncello. Finally stir in the flour and baking powder.
Line a muffin tin with paper liners and pour a well-heaped tablespoon of the batter into each of the liners. Bake in the oven for about 20-25 minutes. Chopstick sample.
Dust with powdered sugar or cover with a lemon glaze.