1. In the bowl of a stand mixer, combine the peanut butter, vanilla, and salt. Beat until smooth and creamy. Gradually beat in the powdered sugar until the mixture crumbly and holds together when pinched between two fingers.
2. Stir the chopped candy in with a spatula.
3. Line a baking sheet with parchment paper. Roll the peanut butter mixture into 1-inch balls and place on the baking sheet.
4. Insert a toothpick into each peanut butter ball and then transfer the baking sheet to the freezer for about an hour, or until the balls are firm.
5. Place the chocolate, coconut oil, and espresso powder in a glass bowl set over a small pot of boiling water, ensuring that the bottom of the bowl does not touch the water.
6. Stir until the chocolate and oil are melted and glossy and the espresso powder has completely dissolved.
7. Dip the frozen peanut butter balls into the chocolate, submerging them a little over halfway. Allow the excess chocolate to drip off and then return the balls to the baking sheet. Once all the peanut butter balls have been dipped, refrigerate them for at least an hour before serving.
8. Remove the toothpicks and serve.

NOTE:

1. These keep best in the fridge but can be stored at room temperature for a day or two (as long as your house isn’t too warm!).