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 microwave safe bowl. Heat 2 -3 minutes, stirring in 30 second intervals until the chocolate has just melted into the condensed milk. Beware not to overheat as the chocolate will seize up and be ruined.

It will be quite thick. 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. 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.