01 - Line an 8-inch square baking pan with parchment paper, allowing overhang on sides for easy removal later.
02 - In a medium saucepan over low heat, combine chocolate chips, sweetened condensed milk, and 2 tablespoons butter. Stir constantly until completely melted and smooth. Remove from heat and stir in 1 teaspoon vanilla extract.
03 - Pour half of the chocolate mixture into the prepared pan, spreading evenly to cover the bottom. Refrigerate for 10 minutes until partially set.
04 - While first layer chills, mix peanut butter, powdered sugar, softened butter, vanilla extract, and salt in a medium bowl until smooth and creamy.
05 - Gently spread the peanut butter mixture over the chilled chocolate layer, working carefully to maintain even coverage.
06 - Pour remaining chocolate mixture over the peanut butter layer and spread evenly to cover completely.
07 - Refrigerate for at least 2 hours or until completely firm throughout.
08 - Lift the fudge from the pan using parchment overhang. Cut into 24 equal squares using a sharp knife, wiping the blade clean between cuts for clean edges.