1) Combine the flour and the icing sugar. Add the egg yolks, vanilla sugar and softened margarine and knead.
2) Form little balls. Flatten slightly, make a little dent in the middle with your thumb and fill with a blob of jam.
3) Place on a baking sheet lined with baking parchment.
4) Bake at 180 °C for 15 – 20 minutes.