To melt the chocolate, put the morsels in a microwave-safe bowl and add the coconut oil or shortening (see Note below). Microwave 30 seconds and stir. Microwave and stir in 10 second increments until chocolate is smooth. Drizzle the chocolate over the prepared peanut butter cookies. Refrigerate 1 hour before serving.
Coconut oil or shortening has to be used to thin the chocolate and not butter. Butter has water in it and, if added, will make the chocolate seize up. I found this out the hard way.