Preheat oven to 340 °F (170 °C).

Cream the butter with sugar, salt, and vanilla sugar.

Mix in the eggs and egg yolks little by little and then carefully fold in the flour.

Using a piping bag fitted with a round nozzle, pipe round cookies onto a baking sheet lined with parchment paper.

Bake for about 12 minutes, leaving the oven cracked open.

Remove from oven and let cool.

Turn over half the cookies and brush with marmalade.

Place the other halves on top.

Melt chocolate and pipe thin lines on the cookies with a piece of parchment paper rolled into a cone.