Preheat the oven to 325°.
Place the walnuts and cashews on a baking sheet and roast in oven for about 8 to 10 minutes, until fragrant but not burnt. Allow to cool completely.
To a food processor, add walnuts 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 eventually start 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’ve 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, and while it's still warm, add in the salt and 1 cup of the chocolate chips.
Process until the chocolate is melted and completey incorporated.
Add in the remaining ½ cup of chocolate chips and stir in until distributed throughout.
Transfer to a jar and keep refrigerated for about a month. You can use this on your toast, pancakes, oatmeal, or just eat it by the spoonful! It tastes like a brownie in a jar!