Preheat the oven to 180°C.
Melt the chocolate in a heatproof bowl set over a pan of simmering water.
Cream the butter and sugar in a food processor until smooth.
Whisk eggs and vanilla extract together, then gradually beat into the butter mixture.
Mix in the melted chocolate.
Toast hazelnuts in a pan until golden, then grind half coarsely and half finely.
Fold the flour and both textures of nuts into the mixture until just combined.
Place twelve heaped tablespoons of mixture onto a tray lined with baking parchment.
Bake for 10 to 12 minutes until the cookies have spread and feel soft.
Cool on the tray briefly then transfer to a rack and serve with fresh fruit.