Preheat oven to 350 degrees F. Coat a 9-inch springform pan with cooking spray and set aside. In a medium bowl, combine the Nutter Butter crumbs (use a food processor to form crumbs or put them into a large ziploc bag and break them down using a heavy spoon) and the butter. Stir until crumbly. Press firmly into the bottom of the prepared pan and bake for 8 minutes in the preheated oven.
In a large bowl, combine the cream cheese, sugar, sour cream, vanilla and eggs. Mix on medium speed (hand-held or stand-up mixer) for 2-3 minutes, or until mixture is smooth.
Stir in the Butterfinger pieces, reserving 1/2 cup. Pour the mixture over the prepared crust and bake for 50-60 minutes in the preheated oven, or until center is cooked through (the center should jiggle with a gentle shake).
Cover and chill for a minimum of 1 hour. Cut into slices and top with reserved Butterfinger pieces.