Place the confectioners’ sugar, vanilla, cornstarch, 2 tablespoons of the flour, spices and cacao in the bowl of a stand mixer. Hand whisk to combine the dry ingredients. Add the butter in cubes. With a paddle attachment mix on low speed 1 for few minutes. Cover the mixer with a kitchen towel to prevent dry ingredients from going all over your counter. At this point you will have a fine crumble texture. Increase to speed 6 and mix for few minutes until well blended.
Transfer dough onto a clean working surface. Add the rest of the flour and knead well with your hand for 2 minutes until you get a nice soft dough. Roll and form into a 5-cm thick log. Wrap with plastic wrap and chill for at least 2 hours.
Line one baking sheet with parchment paper. Preheat oven 190°C/ 375°F. Remove dough from fridge and with a sharp knife cut the log into 4 pieces. Roll each piece into a 2-cm thick rope. Cut 1-cm thick slices. Press one nut in the middle of a slice and roll into a ball in the palms of your hands. Place on prepared baking sheet and bake on 2nd lower for 15-20 minutes. Let cool on a rack and dust with confectioners’ sugar.