Preheat oven to 150C/300F. Spread the nuts out on a baking sheet and toast in the oven for 5-10 minutes.
Whilst the nuts are in the oven, warm the coconut oil and maple syrup in a small pan until melted.
Remove the nuts from the oven, pour over the coconut oil and maple syrup and stir to coat.
Return the baking sheet to the oven and bake for another 10 minutes until the syrup has reduced and the nuts are covered in a sticky glaze. Leave to cool.
Place the nuts into a food processor (affiliate link) and whiz until finely ground. Scrape down the sides of the bowl. Keep the processor running until the nuts release their oils and turn into a smooth butter, about 5-10 minutes.
Add the cocoa powder and salt and keep blending until completely smooth. Taste and adjust the cocoa powder and salt to your liking. Pour into a jar and store at room temperature (or in the fridge if you prefer a firmer nut butter).