Line an 8x8-inch baking pan with parchment paper, leaving some overhang for easy removal later.
In a medium saucepan over low heat, combine the white chocolate chips and sweetened condensed milk. Stir continuously until melted and smooth.
Once the mixture is fully melted, remove it from heat and stir in the peppermint extract and a few drops of green food coloring. Mix well until you achieve your desired shade of green.
Fold in the crushed peppermint candies and chopped nuts if using. Ensure they are evenly distributed throughout the fudge.
Pour the fudge mixture into the prepared baking pan, smoothing the top with a spatula.
Refrigerate for at least 2 hours or until completely set.
Once set, lift the fudge out of the pan using the parchment paper overhang and cut into squares.
Notes
Arrange the fudge squares on a festive plate and sprinkle extra crushed peppermint on top for added decoration.