First, in a bowl, beat the softened butter and sugar with a whisk. Then add an egg and a pinch of salt. Stir again.
Add the juice and zest of an untreated lemon and continue to mix everything together.
Then add the potato starch, the sachet of yeast and the 00 flour, sifting them together.
Transfer the mixture to a work surface and knead until you have a smooth, homogeneous dough.
Cover with cling film and place in the fridge for 30 minutes.
Once this time has elapsed, take the dough and, if you like, add the chocolate chips. I personally love chocolate, so I added a handful to half the dough.
Form small balls and dip them first in caster sugar, then in icing sugar.
Place them on a baking tray, well spaced out, and put them in the fridge for another half an hour.
Preheat the oven at 180°C (356°F). After half an hour you just have to put them in the oven at 180°C (356°F) for about 13 minutes and enjoy their goodness. ;)