01 - Line an 8x8 inch baking pan with parchment paper, allowing excess to overhang for easy removal.
02 - In a large mixing bowl, blend the melted butter and 1 cup of peanut butter until smooth.
03 - Stir in powdered sugar and graham cracker crumbs, then mix in vanilla extract. Continue mixing until a thick, uniform dough forms.
04 - Press the peanut butter mixture evenly into the prepared pan, smoothing the surface with a spatula.
05 - Combine chocolate chips and 1/4 cup peanut butter in a microwave-safe bowl. Microwave in 30-second intervals, stirring after each, until melted and smooth.
06 - Pour the melted chocolate-peanut butter mixture over the base and spread evenly to cover.
07 - Refrigerate for a minimum of 2 hours, or until the top is fully set.
08 - Remove from the pan using parchment overhang. Slice into 16 bars and serve.