01 - Line a 9x13-inch baking dish with parchment paper, leaving overhang on the sides for easy removal.
02 - In a large mixing bowl, blend the creamy peanut butter and melted unsalted butter until smooth and well incorporated.
03 - Fold in the graham cracker crumbs and powdered sugar, stirring until the mixture is uniformly combined and no dry pockets remain.
04 - Transfer the mixture to the prepared baking dish and press firmly into an even, compact layer using a spatula or your hands.
05 - In a microwave-safe bowl, combine the semi-sweet chocolate chips and creamy peanut butter. Microwave in 30-second intervals, stirring between each burst, until fully melted and glossy.
06 - Pour the melted chocolate mixture over the peanut butter base and spread into an even layer with a spatula.
07 - Refrigerate for at least 2 hours or until the chocolate topping is completely firm to the touch.
08 - Lift the slab from the dish using the parchment paper overhang, then cut into 16 even bars and serve.