Preheat the oven to 180 C (fan).
Place the nuts in a food processor and chop them for about 2 minutes, until you have flour.
Add all the other ingredients and pulse until you have a sticky paste.
Roll small balls and place them on a lining baking tray (use a piece of waxing paper for example). Flatten each ball using a spoon or your hands, until you have nice and thin cookies.
Add 1 or 2 pieces of dark chocolate on top of each cookies, pressing down slightly so the chocolate is nicely nested (this is optional but it's a great addition to the cookies).
Put it in the oven for approx. 15-20 min or until brown and crispy. Check it after about 10 minutes to make sure it is not burning, as it depends sometimes on your oven.
Take them out and let them cool down before to eat them up!