Heat oven to 200C/180C fan/gas 6. Toast the hazelnuts in a frying pan over a medium heat until golden. Add the coriander and sesame seeds, and toast for 1 min more. Set aside and leave to cool, then add the ground cumin and bash together using a pestle and mortar.
Peel the butternut squash, remove the seeds and slice into wedges. Toss the wedges with the oil, then mix in the dukkah coating. Spread in a single layer on a baking tray and cook for 30-40 mins, turning halfway through, until tender.