01 - Line an 8x8-inch baking pan with parchment paper, leaving an overhang on all sides for easy removal after setting.
02 - In a medium mixing bowl, combine creamy peanut butter, sifted powdered sugar, melted butter, vanilla extract, and salt. Mix until smooth and well incorporated, then spread evenly across the prepared pan and smooth the top with a spatula.
03 - Place chocolate chips, sweetened condensed milk, and butter in a microwave-safe bowl. Microwave in 30-second intervals, stirring between each interval, until fully melted and smooth, approximately 1 to 2 minutes total.
04 - Pour the melted chocolate mixture evenly over the peanut butter layer, spreading it with a spatula to create a uniform top.
05 - Refrigerate for at least 2 hours or until the chocolate layer is completely set and firm to the touch.
06 - Remove the confection from the baking pan using the parchment paper overhang, then cut into 24 equal squares using a sharp knife.