Slice each date lengthwise to open them up like a book, being careful not to cut all the way through. Remove the pit if it’s still inside.
Spoon about 1 teaspoon of peanut butter into each date. Use the back of the spoon to spread it evenly inside.
Sprinkle chopped peanuts over the peanut butter filling and gently press them in. Close the dates slightly to hold the filling.
Melt the dark chocolate (with coconut oil, if using) in a microwave-safe bowl in 30-second intervals or over a double boiler. Dip each stuffed date in the chocolate, using a fork to coat fully. Let the excess chocolate drip off, then place on a parchment-lined tray.
Refrigerate for 15–20 minutes, or until the chocolate is set.