1. Preheat your oven to 350°F or 175°C.

2. In a large mixing bowl, work the butter until it's light and fluffy.

3. Gradually add the granulated sugar and mix until everything is well combined.

4. Next, add the all-purpose flour, baking powder, and vanilla sugar, and mix until a smooth dough forms.

5. Divide the dough into small balls, roughly the size of a small marble.

6. Roll each ball into a log shape and press down gently to help it hold its form.

7. Place these treats on a baking sheet lined with parchment paper.

8. Sprinkle a pinch of flaky sea salt over them before baking.

9. Bake for 12-15 minutes or until they're lightly golden.

10. Let the treats cool on the baking sheet for a bit before transferring them to a wire rack to cool completely.