1. Preheat the oven to 400°F.

2. Sprinkle half of the powdered sugar on the work surface.

3. Roll out the pastry into a rectangle of 20 x 30 cm. Sprinkle this rectangle with powdered sugar.

4. Fold the 2 large sides of the rectangle towards the middle. Sprinkle with sugar and fold the edges towards the middle again, leaving a space of half a cm in the center.

5. Fold the pastry in half onto itself to form a large log.

6. Refrigerate for 30 minutes.

7. Cut the log of pastry into sections 1 cm thick. Brush with egg yolks. Place the rolls of pastry on a baking sheet, spacing them out.

8. Sprinkle with butter nuts and poppy seeds on half of each palm leaf.

9. Bake for 6 minutes.

10. Remove from the oven, flip the palmiers, sprinkle with poppy seeds and return to the oven for 5 minutes.

11. Remove from the oven and serve.