Preheat the oven to 175 degrees. Seperate the eggs. Beat the eggwhites until stiff. Beat the butter with the icing sugar, the vanilla sugar and the eggs. Add the flour, the baking powder, the cocoa powder, the rum and the grated nuts. Add the beaten eggwhites. Put baking paper onto a baking tray and spread the dough onto the baking tray. Bake the dough in the preheated oven at 175 degrees for 30 minutes. Let it cool down. Mix the sugar with the rum until you have a thick glazing. Spread the glazing evenly onto the dough and decorate it with eatable glitter. Put it into the freezer for 1 hour. With a star shaped cookie cutter cut out stars.