01 - Line an 8x8 inch baking pan with parchment paper, ensuring overhang for easy removal.
02 - In a large mixing bowl, blend melted butter with 1 cup creamy peanut butter until smooth.
03 - Stir in powdered sugar and graham cracker crumbs. Add vanilla extract and mix until a cohesive, thick dough forms.
04 - Press the peanut butter mixture evenly into the prepared pan, smoothing the surface with a spatula.
05 - In a microwave-safe bowl, combine semi-sweet chocolate chips and 1/4 cup peanut butter. Microwave in 30-second increments, stirring after each interval, until melted and silky.
06 - Pour the chocolate-peanut butter mixture over the base layer and spread evenly with a spatula.
07 - Refrigerate for a minimum of 2 hours, or until the bars are fully set.
08 - Remove chilled bars using the parchment paper overhang, slice into 16 even pieces, and serve.