Line a 9x9-inch baking dish with parchment paper, leaving overhang on two sides for easy removal.

Set aside.

In a large saucepan or Dutch oven, combine the sugar, butter, heavy cream, and salt.

Place over medium heat.

Stir continuously until the mixture reaches a boil.

Continue boiling for 5 minutes while stirring constantly.

Remove from the heat.

Immediately add the white chocolate and marshmallow fluff.

Stir until completely smooth and the white chocolate has fully melted.

Gently fold in the broken cookies.

Pour the mixture into the prepared baking dish.

Spread evenly using a spatula.

If desired, sprinkle extra cookie pieces on top while the fudge is still soft.

Allow the fudge to set at room temperature for about 4 hours.

To speed up the process, refrigerate for 1–2 hours or freeze for about 30 minutes.

Once firm, lift the fudge from the pan using the parchment paper sling.

Place on a cutting board and cut into squares using a sharp knife.

Serve at room temperature.