PREHEAT oven to 350ºF. Prepare and bake cake mix as directed on package in two greased and floured 9-inch round cake pans. Loosen layers from sides of pan with knife or metal spatula. Cool 15 min.

STIR boiling water into dry jelly powder at least 2 min. until completely dissolved. Add cold water. Pierce cake layers with large fork at 1/2-inch intervals. Carefully pour half of the jelly mixture over each cake layer. Refrigerate at least 3 hours.

MIX sour cream and icing sugar; gently stir in whipped topping. Dip one cake pan in warm water 10 sec.; unmold onto serving plate. Spread with 1 cup of the whipped topping mixture. Reserve a few cherries for garnish. Chop remaining cherries; sprinkle over cake. Unmold second cake layer; carefully place on first cake layer. Frost top and sides of cake with remaining whipped topping mixture. Drizzle with melted chocolate; garnish with reserved cherries.