Dark Chocolate Peanut Butter Cups

0 In a double boiler, combine the [wprm-ingredient text="6 oz. dark chocolate chips" uid="1"] and [wprm-ingredient text="1 ½ tablespoons unsalted butter" uid="2"]. Heat until the chocolate is melted and smooth. Stir constantly so that the chocolate does not burn. (Alternately, you can melt the chocolate and unsalted butter in a microwave-safe bowl in the microwave at 50% power in 30-second bursts. Keep an eye on it since chocolate burns very easily in the microwave.)
1 As the chocolate melts, place parchment paper liners into a regular-sized muffin tin.
2 Pour about 1 tablespoon of melted chocolate into the bottom of each liner. Use a spoon or small rubber spatula to spread the chocolate around the base, as well as the sides, of the paper cup. (Note: At this point, you should only have used about half of the chocolate. This will go on the top of your peanut butter cups!)
3 Place the muffin tin into the fridge or freezer, and let chill for 30 minutes, or until the chocolate has set.
4 While the chocolate sets, whip the [wprm-ingredient text="½ cup creamy peanut butter" uid="4"], [wprm-ingredient text="¼ cup light brown sugar" uid="5"] and [wprm-ingredient text="½ teaspoon pure vanilla extract" uid="6"] together using the hand mixer in a large bowl. Set aside for later.
5 Remove the chocolate cups from the refrigerator or freezer.
6 Dollop about 1 ½ tablespoons of the peanut butter mixture into the center of each. Spread to even it out with a butter knife or offset spatula to make it an even layer.
7 Top each peanut butter cup with another tablespoon of melted chocolate until the chocolate covers the peanut butter completely and has a smooth layer of chocolate on top. If the chocolate has hardened, reheat over the double boiler or in the microwave in 15-second bursts at 50% power, stirring occasionally until melty.
8 Let set in the refrigerator or freezer for another 15-30 minutes.
9 Remove from the liners and enjoy!