Line an 8″x8″ baking dish with parchment paper on the bottom and all four sides. Set aside.
Using a large heat-proof bowl and a pot, make a double boiler. Heat the water in the pot to a rapid boil, then turn heat down to simmer. To your bowl, add in white chocolate and sweetened condensed milk. Use a spatula to stir constantly until the mixture mixture is fully melted, then remove from heat.
Working quickly, add in cranberries, salt, and almost all of the orange zest (save about 2 teaspoons of zest to sprinkle on top). Pour mixture into prepared baking pan and tap on your counter a few times to remove any unwanted air bubbles. Sprinkle with remaining orange zest.
Cover the baking pan tightly with plastic wrap and place in fridge to set for at least 4 hours, or overnight. Cut into small squares and serve! Will last over a week in the fridge.