Preheat oven to 350 degrees then coat a 9" x 13" cake pan with non-stick spray. In a large bowl, combine cake mix, melted butter and beaten egg until no lumps remain. Press mixture evenly into the bottom of a prepared cake pan then set aside.
Rinse and dry bowl then add melted butter and peanut butter. Mix until completely combined and smooth then stir in beaten eggs, powdered sugar, flour and vanilla. Mix until a smooth mixture forms. Spread evenly over the top of the chocolate layer.
Bake 45–55 minutes or until slightly underdone in center. Remove from oven then place on a rack to cool for 10 minutes.
Meanwhile, melt chocolate chips together with heavy cream in the microwave for 30–45 seconds. Stir until completely combined then drizzle over warm cake. Scoop or slice then serve warm, maybe with a scoop of vanilla ice cream on top!
One Last Thing
This dessert is so good on its own, but a scoop of vanilla ice cream really takes it over the top!