01 - Line an 8x8-inch baking pan with parchment paper, leaving some overhang for easy removal.
02 - In a medium saucepan over low heat, melt white chocolate chips, sweetened condensed milk, and butter, stirring constantly until smooth.
03 - Remove from heat. Stir in vanilla extract and pinch of salt.
04 - Let the mixture cool for 2–3 minutes, then fold in 1 cup of Lucky Charms marshmallows.
05 - Pour the fudge mixture into the prepared pan, spreading it evenly with a spatula.
06 - Sprinkle the remaining ½ cup of Lucky Charms marshmallows evenly over the top, gently pressing them in.
07 - Refrigerate for at least 2 hours or until fully set.
08 - Lift the fudge out of the pan using the parchment overhang and cut into 16 squares.