Line your 8-inch square baking dish with parchment paper, leaving some overhang for easy removal.
In a microwave-safe bowl, combine the chocolate chips and butter. Microwave in 30-second bursts, stirring well each time, until the mixture is smooth and glossy.
Add the creamy peanut butter to the melted chocolate mixture, stirring until fully incorporated and smooth.
Stir in the crushed graham cracker crumbs until evenly distributed, creating a thick, cohesive mixture.
Pour the mixture into the prepared dish, then use a spatula to spread it evenly across the surface, pressing down gently to compact.
Refrigerate uncovered for about 2 hours until the mixture is firm and set, with a shiny, smooth top.
Once chilled, lift the bars out of the dish using the parchment overhang, placing them on a cutting board.
Slice into 12 even squares with a sharp knife, wiping the blade between cuts for clean edges.
If desired, melt a few additional chocolate chips to drizzle over the bars for decoration, then let sit for 10 minutes in the fridge to set.
Serve the bars chilled or at room temperature for a softer bite, and enjoy the rich, nutty flavor with a satisfying firm texture.
