In a large mixing bowl filled with the cake mix, add in the water, oil, butter extract and eggs. Using a hand or stand mixer, mix on medium until well incorporated.
Add batter into the muffin tin until each is about 2/3 full. Sprinkle a bit of the remaining crushed Butterfinger Bits on top of each cupcake. Bake and allow to cool completely before frosting.
Slowly mix in the powdered sugar, 1 cup at a time, while adding a tablespoon of the cream in between each cup. Continue to mix for 1 minute or until creamy. Fold in the crushed Butterfinger Bits.