Prepare and bake the vanilla cake in a 9x13-inch baking dish according to the package directions.
While the cake bakes, scoop approximately 1 quart of the Campfire Peanut Butter Cup Ice Cream into a large measuring cup or bowl and allow it to soften and melt at room temperature. If necessary, microwave in 5–10 second intervals until pourable.
Place your mixing bowl in the freezer while the cake bakes so it is nice and cold when you’re ready to make the whipped cream.
As soon as the cake comes out of the oven, use the handle end of a wooden spoon to poke holes all over the cake, going approximately three-quarters of the way through.
Slowly pour the melted ice cream evenly over the warm cake, concentrating on the holes. Use a spoon or spatula to help guide the ice cream and any chunks into the holes.
Place the peanut butter and hot fudge into separate microwave-safe bowls. Microwave each in 5–10 second intervals until warm and pourable.
Drizzle the peanut butter and hot fudge in a zigzag pattern all over the cake.
Crush 6–7 Keebler Fudge Sticks with your hands and sprinkle them evenly over the cake.
Transfer the cake to the refrigerator while you prepare the whipped topping.
Add the cold heavy whipping cream, powdered sugar and vanilla to your chilled mixing bowl. Beat with a handheld electric mixer until the cream has thickened and is almost at stiff peaks.
Add the marshmallow fluff and continue beating just until stiff peaks form. Do not overmix.
Remove the cake from the refrigerator and spread the marshmallow whipped cream evenly over the top.
Garnish with additional roughly chopped Keebler Fudge Sticks, mini marshmallows and roughly chopped mini peanut butter cups.
Refrigerate until thoroughly chilled, preferably about 2 hours, before slicing and serving.
Serve cold and ENJOY!