Preheat the oven to 180oC (350oF). Place the hazelnuts on a rimmed baking tray and into the oven to toast for 8-10 minutes until they start to smell nutty.
Remove from the oven, tip into a clean kitchen towel and rub between the towel to remove the majority of the outer skin. Pick out the hazelnuts and transfer to a small bowl.
Line the baking tray you were using with a non-stick baking mat (e.g. a silpat mat) or a piece of baking paper.
Heat the sugar in a silver saucepan (you want a silver one so you can see the colour of the sugar change) over a medium-low heat. Once it starts to melt, DON'T stir, just tilt and swirl the pan over the heat until it turns a light golden colour. Once this happens leave it for a little while longer to darken slightly more then stir in the nuts and quickly pour out onto the lined tray.
Leave to cool completely before breaking up into rough chunks - you can either pulse it in a food processor or just chop by hand until it has the texture of coarse breadcrumbs.