Line a 9×13-inch baking dish with parchment paper; set aside.

Bring 3 cups sugar, 3/4 cup butter, and 2/3 cup evaporated milk to a boil in a heavy-bottomed saucepan, stirring constantly; cook and stir at a boil until mixture is smooth, 3 to 5 minutes.

Remove the saucepan from heat. Mix in 2 cups white chocolate chips and 7 oz marshmallow creme until melted, then stir in 1 tsp vanilla. Fold in 1/2 cup crumbled cookies until just incorporated. Spread fudge into the prepared baking dish.

Sprinkle 1/2 cup crushed cookies evenly over the top. Press crushed cookies lightly into fudge. Cool at room temperature until set, then cut into small squares to serve.