Line an 8-inch or 9-inch square baking pan with aluminum foil or parchment paper. Set aside.

In a medium bowl, combine the melted butter, graham cracker crumbs, and confectioners' sugar. Stir in 1 cup (250g) of peanut butter, then press the mixture evenly into the prepared baking pan.

Melt the remaining 2 tablespoons of peanut butter with the chocolate chips, either in the microwave or on the stove. Stir until smooth and spread evenly over the peanut butter layer.

Chill the pan in the refrigerator until the bars are completely firm, at least 2 hours. Let the bars sit at room temperature for 10 minutes before cutting. Serve chilled. It's fine to leave them at room temperature for a few hours before serving.

Cover any leftover bars tightly and refrigerate for up to 1 week.

Freezing Instructions: To freeze, cover the bars tightly, either as a whole or cut into individual squares, and store them in the freezer for up to 3 months. Simply line the squares in a freezer-safe container, separated by sheets of parchment paper. Thaw overnight in the refrigerator before serving.

Special Tools (affiliate links): 8-inch Square Baking Pan or 9-inch Square Baking Pan | Glass Mixing Bowls | Rubber Spatula

Butter: Unsalted butter can be used as a substitute. If doing so, add ¼ teaspoon of salt along with the peanut butter in step 2.

Peanut Butter: For the best texture, I recommend using a processed creamy peanut butter like Jif or Skippy. I do not recommend oily or natural-style peanut butter for this recipe. You can use chunky peanut butter, but the bars may become a little crumbly.

Graham Crackers: If you can’t find graham crackers, substitute them with 120g of ground digestive biscuits (about 8 biscuits).

This recipe was updated in 2019 with additional confectioners’ sugar and peanut butter to create thicker bars.