Stale nuts are totally fine to eat, of course, but they do need to be processed to make them delicious again.
The simplest way to revive a stale nut is by dry roasting or toasting it in a pan over medium heat. However, adding a touch of oil, salt (if using unsalted nuts), some spices, and sweetener will create an incredibly addictive snack out of an ingredient that would otherwise be good for nothing except feeding to the birds.
For an incredible recipe you will need (all items are optional):
• A dash of oil
• Spices: smoked paprika, cumin, cayenne, ginger, cinnamon, etc
• Sea salt OR Sweetener: maple syrup, rice syrup, agave, etc
Heat a heavy-based pan over medium heat. Toast the nuts for five minutes, or until they begin to colour. At this point, you can stop and serve them as they are, or you can flavour them with a variety of toppings. Just a pinch of sea salt will often satisfy, but if you’d like to add spices, do so now with a glug of oil: any spice will do, so take your pick from smoked paprika, cumin, cayenne, etc.
If you want to sweeten them instead, top with a drizzle of maple syrup or honey and let it bubble up and caramelise around the nuts, stirring all the while, then remove from the pan and wait to cool before serving.
Tips adapted from @guardian