In a large skillet set over medium heat, melt ghee and salt then add cashew pieces and roast stirring almost constantly until cashews turn golden and become highly fragrant, about 5 minutes total.
Turn off the heat and let the nuts cool for 10-15 minutes or until they can safely be placed in the bowl of your food processor.
Process for a total of 10 to 15 minutes, stopping to break the lumps and scrape the sides as necessary. You will need to stop a lot more often in the beginning, but as the nuts begin to release their oil, the butter will become a lot looser and scraping won't be needed quite as frequently.
When the nut butter has reached the desired consistency, add vanilla seeds and process for an additional 30 seconds.
Transfer to a clean glass jar and store in the cupboards, where this will keep for several weeks, if it even lasts that long, that is!