Line a 9×9 baking dish with parchment paper and lightly coat it with non-stick spray. Set aside.

In a large pot over medium heat, add the sweetened condensed milk and stir frequently until heated. Mix in the white chocolate chips, sugar cookie mix, and butter. Continue stirring until everything is melted and smooth, then remove from heat.

Mix in a generous amount of Christmas sprinkles.

Pour the fudge mixture into the prepared baking dish and sprinkle more sprinkles on top.

Refrigerate the dish until the fudge is set, ideally overnight or for at least 2 hours. Cut into bite-sized pieces and serve.