Beat the powdered sugar, eggs and vanilla sugar until creamy. Then add the oil and egg liqueur and continue beating. Finally stir in the flour and baking powder. Pour the dough into a greased springform pan and bake at 180 ° C (top / bottom heat) for 50-60 minutes on the middle rack.
Tip: If you don`t like egg liqueur, you can replace it with Baileys or Batida de Coco.