Line the 8x8 inch baking pan with parchment paper, leaving some overhang for easy lifting.
In a medium-sized saucepan, combine the semisweet chocolate chips, sweetened condensed milk, and a pinch of salt. Place the saucepan over low heat.
Stir the mixture continuously using a wooden spoon or spatula until the chocolate chips are fully melted and the mixture is smooth.
Remove the saucepan from the heat and stir in the vanilla extract. Fold in the chopped nuts and half of the crushed peppermint candies, reserving the other half for topping.
Pour the fudge mixture into the prepared baking pan, spreading it evenly with a spatula.
Sprinkle the remaining crushed peppermint candies on top of the fudge.
Allow the fudge to cool to room temperature, then refrigerate for at least 2 hours, or until firm.
Once firm, lift the fudge out of the pan using the parchment overhang. Cut it into 24 pieces using a sharp knife.
For a festive touch, drizzle melted white chocolate on top before adding the crushed peppermint, if desired.