01 - Line an 8-inch square baking pan with parchment paper, allowing excess paper to hang over 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, then remove from heat.
03 - Stir 1 teaspoon vanilla extract into the melted chocolate mixture until fully incorporated.
04 - Pour half of the chocolate mixture into the prepared pan, spreading evenly to cover the bottom. Refrigerate for 10 minutes until slightly set.
05 - While chocolate chills, combine peanut butter, powdered sugar, softened butter, vanilla extract, and salt in a medium bowl. Mix until smooth and creamy.
06 - Gently spread the peanut butter mixture over the chilled chocolate layer, taking care not to disturb the base.
07 - Pour the remaining chocolate mixture over the peanut butter layer and spread evenly to cover completely.
08 - Refrigerate for at least 2 hours until completely firm and set throughout.
09 - Lift the fudge from the pan using parchment paper overhang. Cut into 24 equal squares with a sharp knife.