Line a 13×9-inch baking pan with aluminum foil, ensuring the edges hang over the sides for easy removal. Lightly spray the foil with nonstick spray and set aside.

In a medium saucepan, combine the sugar, butter, and heavy cream. Cook over low heat, stirring frequently, until the sugar has fully dissolved. This process ensures the fudge has a smooth texture.

Increase the heat slightly and bring the mixture to a gentle boil. Stir continuously for approximately 4 minutes to prevent scorching and ensure even cooking.

Remove the saucepan from heat. Immediately add the white chocolate chips and marshmallow crème to the mixture. Stir until the ingredients have fully melted and the mixture is smooth and glossy.

Pour approximately ¾ of the fudge mixture into the prepared pan. Spread it evenly using a spatula. Reserve the remaining mixture in the saucepan for the next step.

Stir the cotton candy flavoring into the reserved fudge mixture until well combined.

Drop or drizzle the cotton candy-flavored mixture over the base layer in the pan. Add 2–3 drops of pink food coloring at various spots on the surface. Use a butter knife to gently swirl the colors together, creating a marbled effect.

Cover the pan and refrigerate for at least 2 hours, or until the fudge has fully set.

Once the fudge is firm, lift it out of the pan using the foil overhang. Remove the foil and place the fudge on a cutting board. Cut it into squares or other desired shapes and serve.