Stir white chocolate, 1/4 cup cream and 2 tablespoons syrup in saucepan over very low heat until chocolate is melted and smooth.
Pour into a bowl and allow to cool 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 tablespoons cream and remaining 2 tablespoons corn syrup to simmer in heavy saucepan over high heat.
Reduce heat to low, add bittersweet or 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, chocolate leaves, or chocolate curls, if desired. Or serve with berries, such as rasberries or strawberries.
Serve with a dollop of chocolate whipped cream.
