Preparation of Pan: Line a 9-inch square baking pan with parchment paper or aluminum foil, ensuring edges extend over the sides for easy removal.
Combining Butter and Peanut Butter: In a large mixing bowl, whisk together melted butter and peanut butter until smooth and well-combined.
Incorporating Powdered Sugar: Gradually sift powdered sugar into the butter mixture, stirring continuously until fully integrated.
Adding Graham Cracker Crumbs: Gently fold in graham cracker crumbs in two separate additions, ensuring each is thoroughly blended into the mixture to achieve a consistent, dough-like texture.
Forming the Base: Transfer the mixture into the prepared pan. Press down firmly and evenly to form a compact and even base layer, paying particular attention to the corners and edges.