Lightly grease a 9-inch deep dished pie pan with cooking spray and set aside. You could also use a springform pan.
In a medium mixing bowl, combine the Oreo cookie crumbs, melted butter, and salt.
2½ cups Oreo cookie crumbs, ½ cup unsalted butter, ⅛ teaspoon salt
Pour the crumb mixture into the prepared pie pan and press it firmly into the bottom of the pan and up the sides. Then place it in the refrigerator to chill while the filling is prepared. This step will help the crust to harden. Do not skip it.
In a large mixing bowl, beat the cream cheese, peanut butter, and powdered sugar until smooth.
8 ounces cream cheese, ¼ cup creamy peanut butter, ½ cup powdered sugar
Fold 2 cups of chopped Butterfingers and half of the thawed Cool Whip into the peanut butter mixture with a rubber spatula until evenly combined and there are no more streaks of white.
2 cups chopped Butterfingers, 16 ounces Cool Whip
Transfer the Butterfinger mixture to the prepared crust and spread it into an even layer.
In a medium mixing bowl, whisk together the chocolate fudge pudding mix and milk for 2 to 3 minutes until it thickens.
2 (3.4 oz) boxes Chocolate Fudge pudding mix, 2½ cups whole milk
Carefully spread the chocolate pudding layer evenly on top of the Butterfinger cream cheese layer.
Spread the remaining Cool Whip evenly on top of the pudding.
16 ounces Cool Whip
Sprinkle with chopped Butterfinger pieces and semisweet chocolate chips. Then drizzle all over with chocolate syrup.
2 cups chopped Butterfingers, 2 tablespoons semisweet chocolate chips, Chocolate syrup
Place in the refrigerator to chill for at least 4 hours or overnight. This will help the layers set and keep its shape when slicing.