Place the dry-roasted peanuts in a food processor. Process for 4 to 7 minutes until the mixture thickens and turns creamy. Pause every couple of minutes to scrape down the sides.
Add the salt and, if using, the honey. Process for another 30 seconds until well mixed.
If the peanut butter is too thick, drizzle in 1 teaspoon of peanut oil at a time and blend until you reach your preferred consistency.