01 - Line an 8x8 inch baking pan with parchment paper, extending paper over the sides for easy removal.
02 - Combine melted unsalted butter and 1 cup creamy peanut butter in a large bowl, stirring until smooth.
03 - Add powdered sugar and graham cracker crumbs to the peanut butter mixture, followed by the vanilla extract. Stir thoroughly until a cohesive dough forms.
04 - Transfer the mixture into the prepared pan, pressing it down evenly with a spatula to create an even layer.
05 - Combine semi-sweet chocolate chips and 1/4 cup creamy peanut butter in a microwave-safe bowl. Melt in 30-second intervals, stirring between each, until completely smooth.
06 - Pour the melted chocolate-peanut butter topping over the base and spread evenly using a spatula.
07 - Place the pan in the refrigerator and chill for at least 2 hours, or until fully set.
08 - Lift the bars out of the pan using the parchment overhang. Cut into 16 even pieces and serve.