Adjust oven rack to the lower third position and preheat the oven to 350°F (177°C). Lightly grease a 9-inch springform pan with nonstick cooking spray. Set aside.
In a food processor or blender, pulse the whole Oreos (cream filling and cookie) into a fine crumb. You should have about 2 cups (packed) crumbs, or 250g. Combine the Oreo crumbs and melted butter together in a medium bowl. Press tightly into the bottom and up the sides of prepared pan. Wrap aluminum foil on the bottom and tightly around the outside walls of the springform pan. This helps prevent leakage.
If you've chosen to substitute the Oreos for something else, be sure to do that in this step.
Bake crust for 10 minutes. Allow to slightly cool as you prepare the filling. Leave oven on.
Using a handheld or stand mixer fitted with a paddle attachment, beat the cream cheese and granulated sugar together on medium speed in a large bowl – about 3 full minutes until the mixture is smooth and creamy. Add the sour cream, peanut butter, and vanilla, beat until combined. On low speed, add the eggs one at a time, beating after each addition until just blended. Do not overmix the filling after you have added the eggs. Using a rubber spatula or large wooden spoon, fold in 3/4 of your chopped Butterfingers. The rest will be for decorating the top of the finished cheesecake.
Be sure to update any substituted ingredients in this step as well.
Pour the filling into the slightly cooled crust. Place the springform pan into a large roasting pan and place into the oven. Fill with about 1 inch of hot water. The foil wrapped around the pan will prevent water from leaking inside. Here’s more information about a cheesecake water bath.
Bake for 50-60 minutes or until the center is almost set.* Turn the oven off and open the door slightly. Let the cheesecake sit in the oven for 1 hour. Remove from the oven and allow to cool completely at room temperature. Refrigerate for at least 6 hours or overnight (preferred).
Loosen the cheesecake from the rim of the pan and remove the rim. Top with additional chopped Butterfingers and drizzle with melted peanut butter. Cut into slices and serve chilled.Cover leftover cheesecake and store in the refrigerator for up to 4 days.