Black and White Cookies
Knead the flour, powdered sugar, salt, vanilla sugar, egg and butter together into a smooth dough. Divide the dough in half. Knead the cocoa powder and a little milk into one half until evenly colored. Wrap both halves in plastic and chill for 1 hour in the refrigerator.
Roll the dark dough on a floured surface into a roll 2cm (approximately 3/4 inch) thick. Roll the light dough out until about 4mm (approximately 1/8 inch) thick and cut into 6.5 cm (approximately 2.5 inch) wide strips. Wrap the dark roll with the strips of light dough, and squeeze the seams. Wrap the rolls individually in plastic and refrigerate again for one hour.
Preheat the oven to 180°C (approximately 350°F).
Cut the rolls into slices approximately 0.5cm (1/4 inch) thick, and place on a lined baking sheet. Back in the preheated oven for about 12 minutes. Remove from the sheet and leave to cool.