Heat the air fryer to 160°C.
If the coconut oil is solid, melt it in a saucepan over a low heat. Alternatively pop it in the microwave in a microwave-safe bowl for 15 seconds at a time, stirring between each burst until completely melted.
Crush the hazelnuts with a large knife then chop into small pieces. Add to a large bowl along with all the other ingredients, except the egg whites.
Add the egg whites to a separate large bowl and whisk until soft and fluffy (this will take around 4-5 mins with a hand whisk). Gently fold the egg white through the dry ingredients.
Add the uncooked granola to the air fryer tray in a single layer (you might need to do this in batches). Cook for 15-20 mins, mixing halfway, until completely golden and toasty.
Leave to cool before serving immediately, or storing in an airtight container for up to 10 days.
