Preheat your oven to 150C.
I roast my nuts in separate oven trays because different varieties have different cooking times. The length of time your nuts will take to roast will vary, but approximate guidelines are as follows:
Pecans: 15 min
Hazelnuts, almonds, sunflower seeds, pumpkin seeds: 20 min
Peanuts: 30 min
Check on them regularly and move them around if they are not cooking evenly, or if the tray is quite full. They are ready when they start to change colour slightly and begin to smell fragrant.
Once the nuts are roasted, allow them to cool completely. If there is a lot of flaky skin coming off the nuts (hazelnuts, for example, shed a lot of skin), rub them between your fingers then remove the nuts from the flakes. Store your cold roasted nuts in airtight containers in the fridge.