01 - Line an 8-inch square baking pan with parchment paper, allowing some overhang for easy removal.
02 - Combine chocolate chips, sweetened condensed milk, and 2 tablespoons butter in a medium saucepan over low heat. Stir continuously until melted and smooth, then remove from heat and stir in vanilla extract.
03 - Pour the chocolate mixture into the prepared pan and spread evenly.
04 - In a separate bowl, blend peanut butter, powdered sugar, melted butter, sea salt, and vanilla extract until smooth and creamy.
05 - Gently spread the peanut butter mixture over the chocolate layer, smoothing the surface with a spatula.
06 - Refrigerate for at least 2 hours until the layers are firmly set.
07 - Lift the fudge from the pan using the parchment paper overhang and cut into 36 small squares with a sharp knife.
08 - Store in an airtight container in the refrigerator for up to 1 week.