Rock-Tastic Chocolate Peanut Butter Cups
While the water starts to boil and the chocolate starts to melt, make the peanut butter ball:
With a spoon, you can draw the chocolate up the sides of the cups until evenly coated (if you like). What I did is make a fat, quarter-to-half-dollar sized disc of PB from the ball and gently pressed it into the hot chocolate at the bottom of the muffin cup, causing it to sort of welled up around the PB disk. Don't press too hard or you will have PB at the bottom of your cup instead of the inside. Both ways work just fine.