The lunch lady at my school growing up used to make these! They were always perfection.

Instructions:
Prepare the Peanut Butter Base: In a large mixing bowl, combine the melted unsalted butter and creamy peanut butter. Stir until they are smooth and well blended.
Add Dry Ingredients: Add the powdered sugar and graham cracker crumbs to the peanut butter mixture. Stir until everything is fully combined and forms a thick, cohesive dough.
Press into Pan: Press this mixture evenly into a 9×13-inch baking dish. Use the back of a spoon or your hands to create a firm, compact base.
Melt Chocolate: In a microwave-safe bowl, melt the semi-sweet chocolate chips. Heat them in 30-second intervals, stirring well in between each interval, until the chocolate is completely smooth and melted.
Top with Chocolate: Pour the melted chocolate evenly over the peanut butter base in the baking dish. Use a spatula to spread the chocolate into a smooth, even layer.
Chill to Set: Refrigerate the bars for at least 2 hours, or until the chocolate topping is completely set and firm.
Cut and Serve: Once the bars are set, remove them from the refrigerator. Cut them into squares of your desired size and serve.