Crumble the dry biscuits and set them aside. Break the dark chocolate into pieces and melt it in the microwave or in a bain-marie, then let it cool. In a separate bowl, add the butter and sugar and beat them with a whisk.
When the butter becomes creamy, add the melted chocolate and also incorporate the Ar.pa unsweetened cocoa. Then mix everything together until you get a smooth mixture.
Add the crumbled biscuits to the mixture. Take a sheet of baking paper and pour the mixture in the center, shaping it into a cylinder. Close the baking paper and twist the ends to seal it.
Place the roll in the fridge for at least 2–3 hours to cool. Once chilled, remove the baking paper and dust the chocolate salami with powdered sugar.
Alternatively, you can make it slightly alcoholic by adding a bit of rum to the mixture.