1. In a small saucepan over medium heat, combine heavy cream, butter, orange zest, and salt. Heat until it just starts to simmer, then remove from heat.

2. Stir in the orange juice and vanilla extract.

3. Pour the hot mixture over the chopped 200g white chocolate in a heatproof bowl. Let sit for 1 minute, then stir until smooth and fully melted. Microwave in short bursts if needed.

4. Cover and refrigerate the ganache for 2 hours until firm.

5. Scoop and roll the chilled ganache into small balls. Freeze them for 30 minutes.

6. Melt the remaining 300g white chocolate gently using a double boiler or microwave.

7. Dip each truffle into the melted chocolate, letting excess drip off, and place on parchment paper.

8. Dust with powdered sugar or extra zest if desired. Let set at room temperature or refrigerate until firm.