01 - Line an 8x8 inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a large mixing bowl, mix melted butter and 1 cup peanut butter until smooth.
03 - Stir in powdered sugar and graham cracker crumbs, then add vanilla extract. Mix thoroughly until a uniform, thick dough forms.
04 - Firmly press the peanut butter mixture evenly into the prepared pan and smooth the top using a spatula.
05 - In a microwave-safe bowl, melt the chocolate chips and 1/4 cup peanut butter together in 30-second intervals, stirring after each until completely smooth.
06 - Pour the melted chocolate-peanut butter mixture over the base and spread evenly.
07 - Refrigerate the assembled bars for at least 2 hours or until fully set.
08 - Once chilled, lift the bars using the parchment overhang, cut evenly into 16 bars, and serve.