Preheat the oven to 350 degrees F (175 degrees C). Butter a 9x13-inch baking pan.
Mix cake mix, peanuts, egg, and butter together in a bowl using an electric mixer until crumbly. Reserve 1 1/2 cups of the mixture; press remaining cookie mixture into the bottom of the prepared pan.
Mix condensed milk and peanut butter together in another bowl. Pour over the cookie mixture in the pan. Sprinkle the reserved cookie mixture over the peanut butter layer. Drizzle caramel syrup on top. Sprinkle chocolate chips over the syrup and press lightly into the cookie mixture using the back of a fork.
Bake in the preheated oven until golden brown, 25 to 30 minutes. Cool and cut into squares.