Preparation Stir white chocolate, 1/4 cup cream and 2 tablespoons syrup in heavy small saucepan over low heat until chocolate is melted and smooth. Pour into medium bowl; cool to barely lukewarm. Using electric mixer, beat 3/4 cup cream in medium bowl to medium-firm peaks. Fold cream into white chocolate mixture in 2 batches. Divide mousse among 4 custard cups. Cover and refrigerate until firm, about 4 hours. (Can be prepared 2 days ahead.) Bring remaining 6 tablespoons cream and remaining 2 tablespoons corn syrup to simmer in heavy small saucepan over high heat. Reduce heat to low; add bittersweet chocolate and stir until melted and smooth. Cool to room temperature. Spoon enough sauce over each mousse to cover completely. Garnish with mint, if desired.
Preparation Stir white chocolate, 1/4 cup cream and 2 tablespoons syrup in heavy small saucepan over low heat until chocolate is melted and smooth. Pour into medium bowl; cool to barely lukewarm. Using electric mixer, beat 3/4 cup cream in medium bowl to medium-firm peaks. Fold cream into white chocolate mixture in 2 batches. Divide mousse among 4 custard cups. Cover and refrigerate until firm, about 4 hours. (Can be prepared 2 days ahead.) Bring remaining 6 tablespoons cream and remaining 2 tablespoons corn syrup to simmer in heavy small saucepan over high heat. Reduce heat to low; add bittersweet chocolate and stir until melted and smooth. Cool to room temperature. Spoon enough sauce over each mousse to cover completely. Garnish with mint, if desired.