Chop the Stracci and hazelnuts in a food processor, then put them in a bowl with 2 tablespoons of cocoa powder. Mix with a wooden spoon, add the Viallella fondente and the normal Viallella, stirring continuously in order to mix all the ingredients together well (if you have a dough mixer better still, the “work” will be easier). When the mixture is smooth and compact, shape it into small balls – using wet hands – measuring roughly 1.5 cm, and place them on a tray covered with greaseproof paper. When you have finished making them, put the tray of truffles in the fridge for 10 minutes.

In the meanwhile melt the bittersweet chocolate in a bain-marie. Take the truffles out of the fridge, dip them, one at a time, in the melted chocolate and then put them back on the greaseproof paper. When they have cooled down completely, sprinkle the remaining cocoa powder over them.