Preheat oven to 180ºC/350ºF. In a large bowl, mix together flour, baking powder, and baking soda.
In another bowl, mix butter, sugar, and vanilla sugar. Add egg, oil, and rum extract to the mixture and beat to combine. Alternately add flour mixture and milk to the butter mixture and stir until dough is combined. Stir in nuts. Line muffin tin, and fill each mold up to ¾ with batter. Bake at 180ºC/350ºF for approx. 20 min., until golden brown. Remove from oven and set aside to cool.
Meanwhile, for the frosting: beat butter until smooth. Add confectioner’s sugar little by little until combined. Add vanilla sugar and cream and beat until fluffy in consistency. Pipe onto cupcakes, then sprinkle shredded coconut over the cupcakes. Garnish with a cinnamon star. Enjoy!