01 - Line an 8x8 inch baking pan with parchment paper, allowing enough overhang for easy lifting after chilling.
02 - In a large mixing bowl, blend melted butter with 1 cup creamy peanut butter until the mixture is smooth.
03 - Incorporate powdered sugar and graham cracker crumbs into the bowl. Add vanilla extract and mix until fully integrated, forming a thick, cohesive dough.
04 - Press the peanut butter mixture firmly and evenly into the prepared pan. Smooth the surface with a spatula.
05 - In a microwave-safe bowl, combine chocolate chips with 1/4 cup creamy peanut butter. Heat in 30-second intervals, stirring between each, until the topping is melted and completely smooth.
06 - Spread the melted chocolate-peanut butter mixture evenly over the base layer.
07 - Transfer the pan to the refrigerator for at least 2 hours or until thoroughly set.
08 - Using the parchment overhang, lift the chilled bars from the pan, cut into 16 equal pieces, and serve.