In a large skillet set over medium heat, melt 2 tablespoons of ghee and then add the cashew pieces; roast, stirring almost constantly until the cashews turn golden and become highly fragrant, about 5 minutes total.
Add the honey and continue cooking, stirring constantly, until the nuts get really sticky and there is no more honey at the bottom of the pan, about 30 seconds.
Process the nuts on medium speed for about 30 seconds to a minute, while pushing down with the tamper to force them into the blades, then slowly increase the speed all the way up to the highest setting. Keep processing until the mixture resembles a block of wet, sticky sand, about 1 or 2 minutes total.
Remove the lid and scrape the sides with a rubber spatula, then add the 1/2 cup of ghee and resume processing, starting on medium and moving up to high, until the nut butter becomes fairly loose and spins freely around the container. Again, use the tamper as needed to push the ingredients into the blades and stop to scrape the sides a few times if necessary. It should take no more than 5 minutes to get the nut butter to completely loosen up.
When the nut butter has reached the desired consistency, remove the lid, add the salt, ground cinnamon and freshly grated nutmeg, scrape the sides one final time if necessary and then give the nut butter a final spin on medium speed, just to incorporate the newly added ingredients, about 30 seconds.
Transfer your nut butter to a clean glass jar and store it in the pantry, where it will keep for up to several weeks, if it ever lasts that long, that is!