Preheat the oven to 325°.
Place pecans and cashews on baking sheet and roast in oven for 10 minutes. Allow to cool completely.
To a food processor, add pecans and cashews, and being processing (this will take some time). You will go through phases in grinding your nut butter. First, you'll see a the nuts break down be coarse, then a fine powder. Keep going! It will start getting rowdy and balling up, looking like a "dough." Keep processing! After it's gone past the dough-ball phase, you will start seeing the nut butter transform into a smooth nut butter consistency. You just gotta keep processing! You can give your machine breaks every now and then to ensure it doesn't overheat.
Once it's turned into butter, add in the rest of the ingredients and process until everything is well incorporated together. If you're using vanilla powder vs. extract, let the nut butter sit for a few hours to really allow the vanilla flavor to bloom throughout.
Now you can use it on your toast, pancakes, ice cream, or just ladle that goodness into your mouth!
Store in a jar in the fridge for about a month.