1. In a robot, mix the butter and sugar, then add the egg yolk as well as the flour and salt. You get a homogeneous dough.

2. Divide the dough into 4 equal portions and shape into rolls of 3-4 cm.

3. Refrigerate for 30 minutes.

Preheat the oven to 350°F (180°C).

4. Cut the rolls of dough into thick slices.

5. Place them on a baking sheet lined with parchment paper and bake for 10-12 minutes.

6. The biscuits should not be colored. Let them cool and sprinkle with vanilla sugar and cinnamon.