Place 2 cups of almonds in a single layer on a large baking sheet
Place the almonds in the oven and toast them for 15 minutes, moving the nuts around a few times during the process.
Allow the almonds to cool until they can be safely handled with your bare hands, then transfer them to the bowl of your food processor; add the remaining 2 cups of almonds, as well as the salt, ground cinnamon and chopped vanilla beans (if using).
Process for a total of about 10-15 minutes, stopping to scrape the sides from time to time, until the butter becomes very smooth and creamy and almost liquid in consistency. It will return to a firmer, more natural state once it's had a chance to rest and cool down.
Transfer to clean air tight glass jars and keep in a cool dry place for up to a few months.
*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. They get pulverized anyway, so why waste?