Step 1: Line an 8×8 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
Step 2: In a medium bowl, combine the melted butter, graham cracker crumbs, powdered sugar, and 1 cup of creamy peanut butter. Stir until well combined and a dough forms.
Step 3: Press the peanut butter mixture firmly and evenly into the bottom of the prepared pan. Use a flat-bottomed cup to smooth it out.
Step 4: In a microwave-safe bowl, combine the chocolate chips and the remaining 2 tablespoons of peanut butter.
Step 5: Microwave in 30-second increments, stirring in between, until the chocolate is completely smooth and melted.
Step 6: Pour the melted chocolate over the peanut butter layer and spread it evenly with a spatula.
Step 7: Refrigerate the bars for at least 2 hours, or until the chocolate is firm. Lift from the pan using the parchment paper and slice into squares.