Instructions

• Line a 9×9-inch or 9×13-inch pan with foil, leaving an overhang on two sides for easy removal, and spray the foil lightly with cooking spray. (You may use any pan size between these—larger pans will produce thinner bars.)
• Measure 8 tablespoons (113 g) unsalted butter and melt it (microwave in short bursts or melt on the stovetop).
• In a large bowl combine the melted butter, 2 cups Ritz cracker crumbs (about 60 crackers or 194 g), 1 1/4 cups (142 g) powdered sugar, and 3/4 cup creamy peanut butter. Mix with a spoon or by hand until the crumbs are evenly coated and the mixture holds together when pressed.
• Transfer the crumb mixture to the prepared pan. Press it firmly and evenly into the bottom of the pan (use the back of a measuring cup or a spatula to compact it).
• Place 1 cup (170 g) chocolate chips and the remaining 2 tablespoons creamy peanut butter in a microwave-safe bowl.
• Melt the chocolate mixture on 50% power in 30-second increments, stirring well between each increment, until smooth and fully combined. (Stop heating as soon as the mixture is smooth to avoid scorching.)
• Pour the melted chocolate-peanut butter mixture over the pressed crust and spread it evenly with an offset spatula or the back of a spoon.
• Chill the pan in the refrigerator for at least 1 hour, or until the topping is set.
• Use the foil overhang to lift the slab from the pan and place it on a cutting board. For cleaner cuts and to avoid the chocolate shattering, let the bars sit at room temperature briefly before slicing into bars.
• Store the bars in an airtight container at room temperature or in the refrigerator, depending on how warm your house is—the chocolate will get melty if it’s too hot.