01 - Line a 9x9-inch baking dish with parchment paper, leaving an overhang on the sides for easy removal.
02 - In a medium bowl, combine the melted butter and 1 cup of peanut butter, stirring until completely smooth.
03 - Add the powdered sugar and graham cracker crumbs to the peanut butter mixture. Stir until thoroughly combined and a thick dough forms.
04 - Press the dough evenly into the prepared baking dish, smoothing the top with a spatula to create a uniform layer.
05 - In a microwave-safe bowl, combine the chocolate chips and 1/4 cup of peanut butter. Microwave in 20-second intervals, stirring after each burst, until fully melted and smooth.
06 - Pour the melted chocolate mixture over the peanut butter base, spreading it into an even layer across the entire surface.
07 - Refrigerate the bars for at least 2 hours, or until the chocolate topping is firm to the touch.
08 - Lift the slab out of the pan using the parchment overhang. Cut into 16 even squares. Store any leftovers in an airtight container in the refrigerator.