01 - Line an 8x8-inch square baking pan with parchment paper, leaving an overhang for easy removal.
02 - In a medium saucepan over low heat, combine chocolate chips, peanut butter, sweetened condensed milk, and salt. Stir constantly until smooth and fully melted, approximately 5 minutes.
03 - Remove saucepan from heat and fold in 1 cup chopped mixed nuts evenly.
04 - Pour the mixture into the prepared pan and smooth the surface with a spatula.
05 - Evenly sprinkle the additional 1/4 cup chopped nuts on top, gently pressing them into the surface if desired.
06 - Refrigerate for at least 2 hours until set and firm.
07 - Lift the fudge out of the pan using the parchment overhang and cut into 24 even squares with a sharp knife.
08 - Store in an airtight container in the refrigerator for up to one week.