Heat sugar without stirring in saucepan to hard crack (150°C), then pour caramel over roasted nuts on sheet tray lined with Silpat, cool to room temperature, then coarsely chop in food processor.

Spread the mixture in an even layer on sheet tray lined with Silpat, then bake at 170°C for 3 minutes to melt sugar, cool to room temperature, then break into crumble.