01 - Line an 8x8 inch baking pan with parchment paper, allowing an overhang for easy removal.
02 - Combine melted butter and 1 cup of creamy peanut butter in a large mixing bowl until smooth.
03 - Add powdered sugar and graham cracker crumbs to the peanut butter mixture, then stir in vanilla extract. Mix thoroughly until a thick dough forms.
04 - Press the peanut butter mixture firmly and evenly into the prepared pan, smoothing the surface with a spatula.
05 - In a microwave-safe bowl, melt chocolate chips and 1/4 cup peanut butter together in 30-second increments, stirring after each interval until smooth and fully melted.
06 - Pour the chocolate-peanut butter mixture over the base and spread evenly with a spatula.
07 - Refrigerate for a minimum of 2 hours or until fully set.
08 - Lift the chilled slab out of the pan using the parchment paper, cut into 16 bars, and serve.