In a large mixing bowl, whisk together the eggs, milk or buttermilk, oil, sour cream, and vanilla extract.

Add in the chocolate cake mix, and mix until lumps disappear.

Place cupcake liners in a muffin pan.

Add 3 tablespoons of cake mix to each cup.

Bake the cupcakes at 350 degrees for 14-17 minutes or until a toothpick inserted comes out clean.

Remove from the oven and allow to cool while you prepare the filling and frosting.

 Add the chocolate chips to a microwave safe bowl.

Pour the cream over the top of the chocolate chips.

Microwave the chocolate and cream at 50% power for 1 minute.

Remove and stir. Continue to microwave at 50% power in 30 second increments, stirring in between, until the chocolate is smooth. Set aside.

Add the softened butter and creamy peanut butter to the bowl of a stand mixer. Beat them together until light and fluffy.

Mix in the vanilla extract and salt.

Add the powdered sugar, one cup at a time, mixing in between.

Add 1 tablespoon of milk or cream and beat the frosting for 1-3 minutes. If the frosting is still too thick, add more milk or cream one tablespoon at a time until you reach your desired consistency. Set aside.

 Unwrap the Butterfinger candy bars and place them in a food processor.

Process until the candy bars become fine crumbs.

Use a sharp knife or cupcake corer to remove the middle of each cupcake and discard.

Add the chocolate ganache to a large piping bag or ziplock bag.

Snip off the end of the bag and fill each cupcake hole with ganache.

Use a cookie/ice cream scoop, about ¼ cup, to scoop peanut butter frosting on to each cupcake.

Carefully cover the frosting in candy bar crumbs.

Use your fingers to re-shape the frosting dome, if necessary.