Spread 260g hazelnuts in a single layer on a baking sheet. Roast them in the oven for about 7-8 minutes, until slightly browned and the skins are blistered a little. Wrap the hazelnuts in a kitchen towel and rub vigorously to remove as much loose skin as possible. Let cool completely.
Place 160g of nuts in the food processor and process for 20-30 seconds, until crumbly.
Add pitted dates, cocoa powder, coconut oil, vanilla extract and salt. Process until combined and sticky.
Take one whole hazelnut, wrap it with the date mixture, then squash the mixture between your hands to form balls. Set aside and place in the fridge while making the coating.
Chop the chocolate and place in a heat proof bowl. Set the bowl over a pot with simmering water (double boiler) and melt the chocolate. Remove from heat, add crushed hazelnuts and mix.
Dip each ball in the melted chocolate and on a parchment paper to set.