If you plan to use a vanilla bean: slice open the vanilla bean lengthwise and remove the pulp and mix it with the ground nuts. (Keep the vanilla bean to make homemade vanilla sugar for your next German baking experience) Separate the eggs. Create a mound with flour, sugar, and ground nuts. (I used hazelnuts in the example). On the top create a little crater and then add in egg yolks. Now cube the cold butter and add on top of the ingredients.
With ideally "cold" hands you knead the ingredients to a smooth dough. (At first, the dough will feel very crumbly and dry. Do not despair, it will come together in time, and if you are struggling add 1 teaspoon of water at a time. You do not want to knead the dough for too long, as you want to avoid it becoming too chewy or elastic.)
Once the dough has come together, wrap it in cling film and place it in the fridge for at least 30 minutes. This will allow the butter to cool down again and makes the dough easier to shape.
Line a baking tray with baking parchment and preheat your oven to 180°C/ 356°F top to bottom heat.
After the chilling time, divide the dough into 2 parts. Roll them each into approximately 30 cm/ 12 inch rolls and then slice them into 1 cm pieces. Roll each piece into an 8-10 cm / 3-4 inches long roll with tapered ends. Carefully bend them into crescent form and place them onto the baking tray.
Bake in the oven, on the middle tray for approximately 12 minutes.
While the cookies are baking, mix 8 teaspoons of vanilla sugar with 3 tablespoons of powdered sugar.