Toast the hazelnuts using one of the following methods until lightly golden and fragrant: Air fryer at 180°C (350°F) for about 3 minutes, oven for 5–6 minutes, or in a dry pan over medium heat, stirring often. Set aside to cool slightly.
Add the toasted hazelnuts, pitted dates, cacao powder and an optional pinch of salt to the large bowl of the food processor.
Blitz, stopping to scrape down the sides if needed, until the mixture changes from crumbly to a uniform, sticky dough that holds together when pressed.
Scoop out a tablespoon of the mixture and roll it between your hands to form a ball. Place on a plate or tray lined with baking paper. Repeat with the remaining mixture. You should end up with 16 balls.
Press a whole hazelnut gently into the top of each ball. Place the tray in the freezer for a few minutes until the balls are firm and set.
Melt the dark chocolate in a heatproof bowl. Roll each chilled ball in the melted chocolate until fully coated.
Transfer the coated truffles back onto the lined tray. Freeze for a few minutes until the chocolate has completely set.
