Yield will vary based on the mold you use. The nutrition data is for the ENTIRE batch. You will need to divide that data by the number of peanut butter cups you end up with.
In a medium pot, combine all ingredients except the peanut butter.
Whisk thoroughly over low heat until the chocolate is smooth.
Using either an oiled silicone mini muffin pan, OR foil cupcake papers in a regular muffin pan, fill the wells 1/3 of the way up with chocolate. Keep the chocolate warmed over low heat if possible or on the warm setting in your slow cooker.
Freeze these for 15 minutes.
Remove them from freezer and add another 1/3 using peanut butter.
Freeze for 15 minutes.
Remove them from freezer and add the last 1/3 with more chocolate.
Freeze for at least 2 hours.
Store in freezer. These get melty pretty quickly, so if you want to serve them but don't want them frozen, put them in the fridge for about 20 minutes, then serve.
Note: These are very good straight out of the freezer.
If you prefer to use a slow cooker, simply melt the chocolate in a small slow cooker and keep the temp low or even on the warm setting if you have one. The chocolate will keep well during the intermittent freezings.
Please note that the nutrition data below is a ballpark figure. Exact data is not possible.