Grease the bundt pan and preheat the oven to 180 degrees (convection: 160 degrees). First, beat the butter with vanilla sugar, sugar and salt until frothy. Then stir in the eggs. Mix the flour, baking powder and cocoa powder in a separate bowl. Alternately stir the mulled wine and the flour mixture into the batter. Fold in the chocolate shavings, pour the batter into the mold. Spread until smooth and bake for about 45 minutes. Let cool down completely. Overturn the bundt cake on a wire rack and turn it once so that the narrow part of the cake is facing up. Mix powdered sugar with mulled wine to a glaze and pour over the cake. Let the casting set for approx. 30 minutes.