In a microwave-safe bowl or double boiler, combine the white chocolate, heavy cream, and unsalted butter. Heat gently, stirring frequently until melted and smooth, about 1-2 minutes in the microwave or 3-5 minutes over low heat.

Let the mixture cool slightly for about 5 minutes before stirring in the finely chopped dried cranberries and chopped pistachios.

Transfer the mixture into a shallow dish and cover it with plastic wrap. Refrigerate for 2-3 hours.

Scoop out small amounts of the firm mixture using a melon baller or tablespoon, rolling them quickly between your palms to form smooth balls.

Pour powdered sugar into a shallow dish and roll each truffle until coated evenly.

Place the coated truffles in an airtight container, separating layers with parchment paper, and store in the refrigerator for up to a week or freeze for up to three months.