01 - Line an 8x8-inch baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a medium bowl, combine peanut butter, powdered sugar, melted butter, vanilla extract, and salt until smooth and well combined. Spread evenly in the prepared pan and smooth the top.
03 - In a microwave-safe bowl, combine chocolate chips, sweetened condensed milk, and butter. Microwave in 30-second increments, stirring between each, until melted and smooth, approximately 1 to 2 minutes total.
04 - Pour the chocolate mixture over the peanut butter layer, spreading evenly to cover.
05 - Refrigerate for at least 2 hours or until fully set and firm.
06 - Remove from the pan using the parchment overhang and cut into 24 uniform squares.