You will need a cake mix, eggs, oil, milk, vanilla, sour cream, chocolate chips, cream, peanut butter, powdered sugar, butter, and Butterfinger candy bars.
To make the cupcake batter, whisk together the eggs, milk or buttermilk, oil, sour cream, and vanilla extract. Add in the cake mix and stir until fully combined.
For the ganache, heat the chocolate chips and cream in the microwave at 50% power for 1 minute then stir. Continue to heat in 30 second increments, stirring in between.
To make peanut butter frosting, beat the butter and peanut butter, then add the powdered sugar, vanilla, and milk. Mix until the frosting is smooth and fluffy.
Unwrap the Butterfinger candy bars and place them in a food processor. Process until the candy bars become fine crumbs. Or crush them in a ziplock bag with a rolling pin.
Assemble the cupcakes by filling the center of each cupcake with ganache, add a scoop of peanut butter frosting on top, and covering the frosting with crushed Butterfinger bars.