Preheat oven to 300°F and prepare cupcake pans with 15 liners.
While the cupcakes are cooling, make the frosting. Cream together the butter and cocoa powder. Add in the powdered sugar one cup at a time, mixing well. Add in the vanilla and salt. Finally, add in the milk or cream, one tbsp at a time, until the frosting reaches a smooth consistency. Transfer to a piping bag and pipe onto the cooled cupcakes. Top each cupcake with a half of a Reese's Peanut Butter Cup, and drizzle with melted peanut butter. Enjoy!
Chocolate Cupcake recipe adapted from Life, Love & Sugar.