Preheat the oven to 350°F. Line a standard muffin pan with cupcake liners. Set it aside.

Add the butter and chopped chocolate baking bar to a microwave-safe bowl. Heat in 30-second intervals, stirring well after each interval, until the butter and chocolate are melted and smooth.

Stir in the granulated and light brown sugar.

Stir in the eggs, mixing well after each egg, until well incorporated.

Stir in the vanilla extract.

Add the flour and stir just until combined. Be sure not to overmix the batter.

Fold in the chocolate chips. Divide the batter evenly between the lined muffin cups. Bake for 22 to 25 minutes, or until a toothpick inserted comes away with a few moist crumbs. Allow the cupcakes to cool completely.

Using either a stand mixer or a medium-sized mixing bowl and a handheld mixer on medium-high speed, beat together the creamy peanut butter, softened butter, and vanilla extract for 1 to 1½ minutes until smooth.

Add the powdered sugar ½ cup at a time, alternating with the heavy cream until completely incorporated and smooth.

Once the cupcakes are completely cooled, fill a piping bag fitted with an open star tip (Wilton’s 1M decorating tip) or a gallon-size ziplock bag with the corner snipped off with the frosting.

To frost the cupcakes, hold the piping bag about ½ inch from the center surface of the cupcake. Use even pressure, and squeeze to form the center of the star swirl. Keeping the tip elevated and using the same pressure, follow the outer line of the star-swirl, making a C shape around the star-swirl until the outer swirl lines connect. Repeat for the remaining cupcakes. Sprinkle the frosting with the crushed Butterfinger candy and top with a halved fun-size Butterfinger.