01 - Line an 8x8 inch baking pan with parchment paper, leaving overhang for easy removal.
02 - In a large mixing bowl, blend melted unsalted butter with 1 cup creamy peanut butter until smooth.
03 - Integrate powdered sugar and graham cracker crumbs into the peanut butter mixture, add vanilla extract, and stir until a thick, cohesive dough forms.
04 - Press the mixture firmly and evenly into the lined pan, smoothing the surface with a spatula.
05 - Using a microwave-safe bowl, melt semi-sweet chocolate chips with 1/4 cup creamy peanut butter in 30-second intervals, stirring between each, until the mixture is glossy and smooth.
06 - Pour the melted chocolate-peanut butter over the base and spread evenly.
07 - Refrigerate for at least 2 hours, or until the bars are fully set.
08 - Lift out the dessert using parchment overhang, cut evenly into 16 bars, and serve.