01 - Line an 8-inch square baking pan with parchment paper, allowing excess paper to hang over the sides for easy removal later.
02 - Combine chocolate chips, sweetened condensed milk, and 2 tablespoons butter in a medium saucepan over low heat. Stir continuously until completely melted and smooth. Remove from heat and blend in 1 teaspoon vanilla extract.
03 - Transfer half of the chocolate mixture to the prepared pan, spreading it into an even layer. Place in refrigerator for 10 minutes to partially set.
04 - While first layer chills, combine creamy peanut butter, powdered sugar, softened butter, ½ teaspoon vanilla extract, and salt in a medium bowl. Mix until completely smooth and well blended.
05 - Carefully spread the peanut butter mixture over the chilled chocolate layer, maintaining an even thickness.
06 - Pour the remaining chocolate mixture over the peanut butter layer and spread evenly to cover completely.
07 - Refrigerate the fudge for a minimum of 2 hours or until completely firm and set throughout.
08 - Using the parchment paper overhang, lift the fudge from the pan. Cut into 24 equal squares using a sharp knife, wiping the blade clean between cuts for clean edges.