Place 2 cups of almonds and the 2 cups hazelnuts on a large baking sheet, making sure to keep them well separated so the nuts don't mix.
Toast in the oven for 15 minutes, moving the nut around a few times during the process.
Place the hazelnuts in a clean tea towel and close that up into a little bundle. Now hold that package in one hand and, with the other hand, wiggle the nuts around so that they grind against each other. Do that for a good minute or so and when you open up your little bundle, your hazelnuts will be totally skinless. Now carefully pick the nuts out, leaving the skins behind.
Add the toasted almonds, hazelnuts and raw almonds, as well as salt and chopped vanilla beans* to the bowl of your food processor
Process for a total of about 20 minutes, stopping to scrape the sides from time to time, until the butter is very smooth and creamy and almost liquid in consistency. It will return to a firmer consistency once it's had a chance to rest and cool down.
Transfer to clean air tight glass jars or containers.
*yes, I actually throw the whole thing in there, not just the seeds. I only take care to remove the dry ends, then chop the whole vanilla beans very finely before I add them to the food processor