Preheat the oven to 180°C .

Take the butter out of the fridge to allow it to soften.

1. Weigh all of the dry ingredients into a large mixing bowl: flour, Zùsto, vanilla powder, salt.
2. Mix all the dry ingredients together.
3. Weigh the butter and separate the egg.
4. Beat the yolk with 1 tablespoon of water.
5. Add the diced butter to the dry ingredients.
6. Knead the dough well with your hands.
7. Add the yolk and water to the dough.
8. Knead the dough with your hands into a firm ball.

The heat from your hands will melt the butter, giving the dough its shape.

9. Melt the chocolate in a bain-marie.
10. Divide the dough into 2 equal halves, and mix in the chocolate with one half of the biscuit dough.
11. Wrap the dough in clingfilm and put it in the fridge for 25 minutes

If the dough goes into the oven cold, the cookies won’t turn out as hard and will have a crispness to them.

12. Remove the dough from the foil and flour your work surface.
13. Take one piece of chocolate dough and one piece of sand dough. Roll them into tubes.
14. Shape them like a spiral staff
15.       Bake the cookies until golden brown for 13-15 minutes.