Prepare the Pan: Line a 9x13-inch baking pan with parchment paper, leaving a bit overhanging for easy removal.
Make the Base: In a large bowl, stir together melted butter, peanut butter, vanilla, and salt until smooth. Add powdered sugar and graham cracker crumbs. Mix until well combined and thick.
Press Into Pan: Press the mixture evenly into the prepared pan, smoothing the top with a spatula.
Make the Topping: In a microwave-safe bowl, combine chocolate chips and peanut butter. Microwave in 30-second bursts, stirring between each, until smooth.
Spread the Chocolate: Pour the chocolate mixture over the peanut butter layer. Smooth it out evenly.
Chill: Refrigerate for at least 2 hours or until firm.
Slice & Serve: Use the parchment overhang to lift the bars out. Slice into squares and enjoy!