Place almonds in the bowl of the food processor or blender.
Puree, scraping down the sides with a spatula as necessary, until almond butter forms. The almonds will first turn into a meal-like consistency, and then after about 10 minutes finally form a very thick almond butter. Keep going; the almonds will release their oils and transform into a delicious spreadable almond butter after about 12-15 minutes total time. Add salt toward the end of the process if desired.
Keeps refrigerated in an airtight container for up to 2 weeks. Note: keep an eye on your food processor or blender. If it shows signs of overheating, take a break for a few minutes before continuing. You know your equipment; err on the side of caution!