01 - Line an 8x8 inch baking pan with parchment paper, leaving some overhang for easy removal.
02 - In a large mixing bowl, blend melted unsalted butter with 1 cup creamy peanut butter until completely smooth.
03 - Incorporate powdered sugar and graham cracker crumbs into the peanut butter mixture, then add vanilla extract. Stir thoroughly until a dense dough forms.
04 - Transfer the mixture to the prepared pan and press it evenly, smoothing the surface with a spatula.
05 - Melt semi-sweet chocolate chips and 1/4 cup peanut butter together in a microwave-safe bowl using 30-second intervals, stirring after each until a glossy, smooth consistency is achieved.
06 - Pour the melted chocolate-peanut butter mixture evenly over the pressed base and smooth the top.
07 - Place pan in the refrigerator and chill for at least 2 hours or until bars are completely firm.
08 - Once set, lift the bars out with the parchment paper, cut into 16 even squares, and serve.