Line a baking sheet with parchment paper. Spread peanuts over baking sheet in an even layer, then layer the peanut butter cups on top. Roast in the oven until peanuts become fragrant, 5-7 minutes.
Let cool slightly, then lift the parchment and pour peanuts and peanut butter cups into a food processor. Process for about 5 minutes until you have a smooth peanut butter, scraping down the sides as needed.
Add powdered sugar, cocoa powder, vanilla, salt and coconut oil to your food processor and blend for about a minute until the consistency of smooth peanut butter. Add more salt and coconut oil to suit your tastes. Will keep in an airtight container in the fridge for a week or so.