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. Stir until completely smooth. Add the powdered sugar and graham cracker crumbs, then mix thoroughly until a thick, uniform dough forms.
03 - Transfer the dough into the prepared baking dish. Press it down evenly using a spatula, smoothing the top surface to create a flat, even layer.
04 - Place the chocolate chips and 1/4 cup of peanut butter in a microwave-safe bowl. Microwave in 20-second intervals, stirring between each interval, until the mixture is fully melted and glossy.
05 - Pour the melted chocolate mixture over the peanut butter base, spreading it into an even layer across the entire surface.
06 - Place the dish in the refrigerator and chill for at least 2 hours, or until the chocolate topping is firm to the touch.
07 - Lift the chilled slab out of the dish using the parchment paper overhang. Place on a cutting board and slice into 16 even squares.