12ouncessemi-sweet chocolate chips (a tad more than 2 cups)
Have ready a large baking sheet lined with wax or parchment paper.
Cream together the confectioners sugar, peanut butter, butter and vanilla.
Use your hands to roll 1-1/2 - inch balls from this mixture, placing them onto the prepared baking sheet. (You can also use a tablespoon-sized cookie scoop, and then roll the ball quickly in your hands to smooth it.) Refrigerate the balls for 3-4 hours until they are very firm.
In the top of a double-boiler, heat and stir the chocolate and the vegetable shortening until they're melted and smooth.
Have another sheet of wax or parchment paper ready on a baking sheet where you will place the chocolate-coated balls.
Spear a chilled peanut butter ball with a toothpick, or place it on the tines of a fork, and lower it into the melted chocolate. Coat it thoroughly using a spoon to get the entire surface covered. Place the ball on the wax paper. Repeat these steps with all of the peanut butter balls. Allow them to cool for 1-2 hours until the chocolate is set.
Store the balls in an airtight container at room temperature. They will last for up to 1 week - if by some remarkable chance they do not all get eaten in the first 24 hours!
Some people have asked if natural peanut butter can be used in this recipe. Regular peanut butter has a consistent, stable emulsion. Natural peanut butter however has a less stable emulsion and the oil is usually separated. Using natural peanut butter in this recipe will yield a sticky result that may not hold the shape or hold up to dipping. Therefore, I recommend using regular peanut butter for this recipe.