Line a standard 12-cup muffin tin with liners. Set aside.
In a medium bowl add peanut butter, butter, and confectioners' sugar. Use a hand mixer on low and combine all of the ingredients. Set aside.
Add the chocolate to a microwave-safe bowl. Heat in 20-second increments, stirring after every 20 seconds, until the chocolate is melted and creamy (about 1-2 minutes total).
Add about 1 tablespoon of chocolate to the bottom of each muffin tin (only enough to fully coat the bottom of the liner). Top with 2 heaping teaspoons of the peanut butter mixture in the center. Add about 1 tablespoon of chocolate to the top of each cup. Carefully tap the muffin tin onto the counter to help the chocolate settle and smooth out the tops.
Chill in the refrigerator for 1 hour, or until set, before serving.
