**Prepare the Pan:** Line an 8x8-inch baking dish with parchment paper, leaving a slight overhang for easy removal.

**Melt the Base Ingredients:** In a medium saucepan, combine white chocolate chips, sweetened condensed milk, and butter. Heat over low heat, stirring constantly, until smooth and fully melted. Remove from heat and stir in vanilla extract.

**Divide the Mixture:** Pour half of the fudge mixture into a separate bowl. Add the red gel food coloring and apple extract to one half, stirring until evenly colored and flavored. Add the black gel food coloring to the other half and mix until fully combined.

**Layer and Swirl:** Pour the red fudge into the prepared pan, spreading it evenly with a spatula. Dollop spoonfuls of the black fudge on top, then use a toothpick or skewer to create swirls and patterns.

**Chill the Fudge:** Place the pan in the refrigerator and let the fudge set for at least 3 hours, or until firm.

**Cut and Serve:** Once set, lift the fudge out of the pan using the parchment paper. Cut into squares and serve.