Preheat the oven to 350℉ and line a baking sheet with parchment paper. Scatter the cashews onto the baking sheet and pour over the honey, tossing to coat them evenly.
Bake the cashews for 10-15 minutes, using a spatula to toss the nuts every 5 minutes so they toast evenly. Once browned, remove the pan from the oven and allow to cool slightly.
Place the cashews into the bowl of a food processor fitted with a blade attachment. Allow the machine to run until a nut butter forms, scraping down the sides every few minutes. It will turn from a crumbly flour to a thick paste, then nut butter (this could take up to 10 minutes). The longer you process it, the runnier the butter will be.
Once a nut butter forms, add the cocoa powder and salt and process until evenly incorporated. Scrape the nut butter into an airtight container or jar and store at room temperature (or in the fridge) for around a month.