Place peanuts and Oreos in a food processor and run continuously until butter forms. Time will vary depending on your food processors age and speed. Mine took about 4 minutes to reach a creamy, buttery consistency.
If your processor is older, or starts to feel hot during processing, stop the machine and let it rest a few minutes before continuing.
Serve on toast, as a dip, or with a spoon.
Notes
If your mixture is too thick, you can add vegetable oil (about 1 tablespoon) to thin it.