Grease and line an 8x8 inch baking pan with parchment paper.
In a large heavy-bottomed saucepan, combine sugar, evaporated milk, butter, and salt.
Cook over medium heat, stirring constantly, until the mixture comes to a boil.
Reduce heat to low and simmer, stirring constantly, for 5 minutes.
Remove from heat and stir in vanilla extract and cotton candy flavoring.
Divide the mixture into two equal parts. Tint one part pink and the other blue with food coloring. Swirl the colors together gently, being careful not to overmix.
Pour the swirled mixture into the prepared pan. Smooth the top with a spatula.
Let the fudge cool completely at room temperature for at least 4 hours, or until firm.
Once firm, lift the fudge out of the pan using the parchment paper. Cut into squares.
Notes
Store fudge in an airtight container at room temperature for up to a week.