In a small saucepan, melt the butter over low-medium heat. Add the heavy cream and stir until combined. Stir in a pinch of salt and the orange or vanilla extract, if using. Set aside to cool slightly.
Place the chopped white chocolate in a heatproof bowl over a double boiler. Stir gently as it melts until smooth and fully melted. Important: Do not overheat the chocolate. Keep the temperature below 105°F to prevent separation.
Using a rubber spatula, gently fold the lukewarm butter and cream mixture into the melted white chocolate. Ensure both are at similar temperatures.
Stir in the chopped cranberries and pistachios until evenly distributed. Cover the mixture with plastic wrap pressed onto the surface.
Let the mixture rest at room temperature for 1 hour, then refrigerate for 2–3 hours until firm.
Scoop out portions with a melon baller or spoon, and roll into 1-inch balls. Wipe hands as needed to prevent sticking.
Roll each truffle in powdered sugar until fully coated.
Refrigerate in an airtight container for up to 1 week, or freeze for longer storage.
