Line an 8×8 baking dish with parchment paper. Set it aside.

Using a medium-sized heat-safe mixing bowl, add the white chocolate chips.

Pour the sweetened condensed milk over the white chocolate chips. Microwave for 45 seconds. Stir. Microwave for another 15 seconds and stir until smooth.

Fold in the chopped dried cranberries and chopped unsalted pistachios.

Evenly spread the mixture into the prepared baking dish.

Tear a piece of wax paper and spread the teaspoon of unsalted butter onto the wax paper.

Evenly press the buttered wax paper on top of the fudge. Gently smooth fudge. Remove the wax paper. Tightly cover the pan and chill in the refrigerator for 2 hours.

Remove the fudge from the refrigerator.

Using a cutting board and a sharp knife, carefully cut 1½ inch x 1½ inch squares.