01 - Line an 8x8-inch baking pan with parchment paper, allowing the sides to overhang for easy removal later.
02 - In a medium saucepan over low heat, combine the white chocolate chips, sweetened condensed milk, and butter. Stir constantly until the chocolate is completely melted and the mixture becomes smooth and glossy.
03 - Remove the saucepan from heat and immediately stir in the peppermint extract until evenly distributed throughout the mixture.
04 - Pour approximately three-quarters of the fudge mixture into the prepared pan. Spread it evenly using a spatula to create a smooth base layer.
05 - Add several drops of red gel food coloring to the remaining fudge mixture in the saucepan. Stir thoroughly until the color is uniformly distributed.
06 - Drop spoonfuls of the red fudge mixture over the white layer in the pan. Use a knife or skewer to gently swirl through both layers, creating a decorative marbled pattern. Avoid over-swirling to maintain distinct color contrast.
07 - Sprinkle the crushed peppermint candies evenly across the surface of the swirled fudge. Gently press the candies into the mixture to ensure they adhere properly.
08 - Refrigerate the pan for at least 2 hours, or until the fudge is completely firm and set throughout.
09 - Lift the fudge block from the pan using the overhanging parchment paper edges. Cut into squares and serve immediately or store for later use.