01 - Line an 8x8 inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a large bowl, mix melted butter and 1 cup creamy peanut butter until smooth.
03 - Stir in powdered sugar and graham cracker crumbs, followed by vanilla extract. Blend until a thick, uniform dough forms.
04 - Press the peanut butter mixture evenly into the prepared pan, smoothing the top with a spatula.
05 - Melt chocolate chips with 1/4 cup peanut butter in a microwave-safe bowl, heating in 30-second intervals and stirring until smooth.
06 - Pour melted chocolate-peanut butter mixture over the base and spread evenly to cover.
07 - Refrigerate for at least 2 hours or until fully set.
08 - Remove the set bar from the pan by lifting the parchment. Cut into 16 bars and serve.