In a small saucepan, melt the butter over low-medium heat. Add the heavy cream and stir until combined.
Stir in salt and optional orange or vanilla extract. Let cool slightly.
Melt white chocolate gently in a double boiler. Do not exceed 105°F.
Fold cream mixture into melted chocolate gently using a spatula.
Stir in chopped cranberries and pistachios. Cover and rest 1 hour, then chill for 2–3 hours.
Scoop and roll into 1-inch balls using your hands.
Roll each truffle in powdered sugar until coated.
Refrigerate in airtight container for up to 1 week.
