In a 12-cup food processor fitted with an "S" blade, add in the cashews and start processing. They will break down into a flour-like, powdery consistency and will start piling up against the sides of the food processor bowl within 2 minutes.
Stop and scrape down the sides, then start processing again. It will take roughly 5 minutes total for the mixture to form a ball. This is a good sign.
Continue processing. The cashew butter will start to look thick and grainy when the ball breaks down, and it will continue getting smoother the longer you process it. After roughly 10 minutes total of processing, you should begin to hear a loud "sloshy" sound as the cashew butter becomes runnier in texture. This is when you know it's done.
Transfer the cashew butter to a clean glass jar with a lid, and store it in the fridge. It should last for at least a month in the fridge, as long as you keep it free from added moisture.