In a medium microwave-safe bowl add ¼ cup of peanut butter, chocolate chips, and the broken-up chocolate bar.
Microwave for 15 seconds at a time, stirring in between until chocolate is melted and well combined, about 2 minutes. Reserve half the chocolate for the top layer.
Pour half of the melted chocolate equally into the paper liners. Tap the pan lightly on the counter to even out the chocolate layer. Refrigerate for 10-15 minutes.
In a small measuring cup melt the remaining peanut butter in the microwave at 10-second intervals until melted, about 20 seconds.
Pour a small dollop of the peanut butter on top of the first layer of chocolate equally among the paper cups. Don’t overfill the peanut butter because when you top the cups with the remaining chocolate, it will spill over.
Top with the remaining chocolate.
Refrigerate until set.
Notes
Do not overheat the chocolate. it as it can seize and become grainy.Each layer of chocolate and peanut butter should be chilled before adding the next to maintain distinct layers. After each chocolate layer, lightly tap your muffin tin on the counter to remove air bubbles and help the chocolate settle into a smooth layer.Make sure to chill your peanut butter cups in the refrigerator for at least an hour or until the chocolate is completely set. This will make them easier to eat and keep the layers distinct.