Roughly chop the chocolate. Melt butter and chocolate in a small pot at low heat while stirring. Remove from the stove. Roast the nuts in a pan without fat, take them out and chop them roughly. Whisk eggs, vanilla sugar, salt and sugar with the whisk of the hand mixer. Stir melted butter and chocolate into the egg mixture. Mix flour, baking powder and gingerbread spice and stir in alternately with the milk.
Fold in nuts. Grease the fat pan of the oven (32 x 39 cm) well. Spread the dough evenly over it. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 30-35 minutes. Remove from the oven and let cool on a cake rack. Cut a star template from a piece of paper (approx. 3 cm Ø). Cut the cake into 48 pieces and sprinkle a star on each piece using the template and icing sugar