01 - Line an 8x8 inch baking pan with parchment paper, allowing excess to overhang for easy removal.
02 - In a large bowl, combine melted butter and 1 cup peanut butter and mix until smooth.
03 - Stir in powdered sugar and graham cracker crumbs, then add vanilla extract. Mix thoroughly until a dense dough forms.
04 - Press the peanut butter mixture 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 intervals, stirring between each, until smooth.
06 - Pour the chocolate-peanut butter mixture over the base and spread evenly.
07 - Refrigerate the pan for at least 2 hours or until completely firm.
08 - Once chilled, lift the bars out using the parchment paper, cut into 16 pieces, and serve.