Line two 24-count mini-muffin tins with paper liners or a large baking sheet but place very closely together (I didn’t have a mini muffin tin). Set pan aside.
In a medium saucepan, combine the peanut butter, butter and brown sugar over medium heat. Heat until completely melted and starting to and stir constantly. Remove from the heat. Add the powdered sugar a little at a time, and stir until completely combined. Set aside and let cool.
Meanwhile, put the chocolate chips and shortening into a microwave safe bowl. Melt them together in the microwave, stir every 30 seconds until the chocolate has completely melted.
Use a tablespoon to spoon in some of the melted chocolate into the bottom of the muffin liner. Place in the refrigerator for 30 minutes until cooled and hard.
Use a teaspoon to scoop out the peanut butter mixture and place on top the chilled chocolate. Press into the muffin liner to spread peanut butter across the top of the chocolate. Once finished place back into the refrigerator to let chill.
Remove from the refrigerator and top off with another layer of chocolate. Make sure the top of the chocolate layer is smooth. Place back into the refrigerator for another 30 minutes. Make sure you repeat this process until all chocolate and peanut butter has been used. Refrigerator until ready to serve.