Line an 8-inch square baking pan with parchment paper, letting paper extend over edges of pan by 2 inches. Spray parchment paper with baking spray.
In a medium saucepan, bring to a boil together sugar, cream, butter, and salt over medium heat, stirring constantly, until a candy thermometer registers 234°. Remove from heat. Vigorously stir in white chocolate, marshmallow crème, and vanilla extract until combined. Fold in pistachios and cranberries. Pour fudge into prepared pan.
Sprinkle fudge with chopped pistachios, if desired. Let cool to room temperature. Refrigerate until cold and set, at least 4 hours, before cutting into 64 (1-inch) squares.
Recipe by TeaTime Magazine at https://teatimemagazine.com/pistachio-cranberry-white-chocolate-fudge/