01 -
Preheat oven to 350°F. Line a 9×13-inch pan with aluminum foil and spray with cooking spray. Set aside.
02 -
Prepare cake mix according to the package directions, adding eggs, water, and oil as instructed. Pour into prepared pan and bake as directed (approximately 23 to 28 minutes).
03 -
While the cake bakes, place the peanut butter in a large microwave-safe bowl and heat for 15 to 30 seconds until softened. Add the sweetened condensed milk and caramel topping, and whisk together until smooth. Set aside.
04 -
Once the cake has finished baking, remove it from the oven and use the blunt end of a wooden spoon to poke about 60 evenly spaced holes across the surface.
05 -
Slowly pour the peanut butter, sweetened condensed milk, and caramel mixture over the holes, ensuring even distribution. Place the cake in the refrigerator for 10 minutes to cool slightly before proceeding.
06 -
Remove the cake from the refrigerator and evenly spread the whipped topping over the surface. Sprinkle the peanut butter chips and halved mini peanut butter cups evenly on top.
07 -
Cover the cake and refrigerate for at least 2 hours (overnight is best) before slicing and serving.