Line a 9x9-inch baking dish with parchment paper. Set aside.

In a large saucepan over medium heat, combine sugar, butter, heavy cream, and salt. Bring to a boil while stirring constantly.

Let the mixture boil for 5 minutes, stirring continuously.

Remove from heat. Add white chocolate chips and marshmallow fluff. Stir until smooth.

Fold in the chopped Oreo cookies.

Transfer the fudge to the prepared baking dish. Let it set at room temperature for about 4 hours. For a quicker setting, chill in the refrigerator.

Serve the fudge at room temperature.