Line an 8-inch square baking dish with foil, leaving enough overhang on the sides to easily pull the fudge out once it is set. Set aside.

Combine the sweetened condensed milk and white chocolate chips in a medium saucepan over medium heat. Stirring constantly, cook until the white chocolate has melted completely and the mixture is smooth. It will be quite thick. Once smooth, remove from the heat and stir in the vanilla and salt. Then stir in the cranberries and pistachios until evenly combined. Pour into the prepared dish and smooth the surface with a rubber spatula.

Cover the fudge with foil and refrigerate for 4 hours, or leave at room temperature overnight. Once set, lift the fudge out of the dish using the foil overhang. Turn the fudge upside down to remove the foil, then turn right side up on a cutting board. Cut the fudge into 1-inch squares.