01 - Place finely chopped white chocolate in a heatproof bowl.
02 - Heat heavy cream and butter in a small saucepan over medium heat until just simmering, avoiding a boil.
03 - Pour hot cream mixture over chopped chocolate. Let stand 2 minutes, then stir gently until smooth and completely melted.
04 - Fold crushed freeze-dried raspberries into the chocolate ganache until evenly distributed.
05 - Cover bowl and refrigerate for at least 2 hours until mixture firms enough to scoop.
06 - Scoop portions with a small spoon or melon baller and roll into smooth balls with hands. Place on parchment-lined tray.
07 - Chill rolled truffles for 15 minutes to firm before coating.
08 - Dip each truffle in melted white chocolate, allowing excess to drip off, then return to lined tray.
09 - While coating remains tacky, dust each truffle with powdered sugar and optionally sprinkle with raspberry powder.
10 - Let truffles stand at room temperature until coating is completely firm before serving.