Toast the hazelnuts until a deep dark brown colour is formed. Approx. 8 minutes.Immediately transfer the toasted hazelnuts off the hot tray to a plate to cool. Add the salt while they are still hot.
Heat up a small pan with high sides and fill ⅓ with water (make a double boiler). Chop the chocolate roughly and place it in a metal bowl. Heat the bowl of chocolate over the hot water to gently melt it. (Bain-marie)
Once the hazelnuts are toasted blitz them while they're still hot with the sugar in the food processor until a hazelnut butter is formed. Add the melted chocolate and continue to blend.
Store in a sealed mason jar at room temperature for up to 3 days. Enjoy!
Notes
Be careful when working with chocolate to not add any water as it can "seize".Always wipe the bowl clean of any water before adding the chocolate to the bowl. Take care not to drip water into the chocolate when pulling the melted chocolate bowl off the boiling water.Don't store this in the fridge as it will thicken up too much.