- Stir white chocolate, 1/4 cup cream and 2 tbsp  syrup in saucepan over very low heat until chocolate is melted and smooth. 
- Pour into a bowl and allow cooling to lukewarm. 
- Beat 3/4 cup cream with electric mixer to firm peaks. 
- Fold cream into the white chocolate mixture in 2 batches. 
- Divide mousse among 4 custard cups. 
- Cover and refrigerate until firm, about 4 hours. 
- Can be prepared up to 2 days ahead. 
- Bring remaining 6 tbsp  cream and remaining 2 tbsp  corn syrup to simmer in heavy saucepan over high heat. 
- Reduce heat to low, add semi-sweet chocolate and stir until melted and smooth. 
- Cool to room temperature. 
- Spoon enough sauce over each mousse to cover completely. 
- Garnish with mint leaves, and with a dollop of chocolate whipped cream.