PREPARE and bake cake mix in two 8- or 9-inch round layers as directed on package. Run knife or metal spatula around sides of pans to loosen cakes. Cool in pans 15 min.

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

MIX sour cream and powdered 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 frosted layer. Unmold second cake layer; carefully place on cake layer on plate. Frost top and side of cake with remaining whipped topping mixture. Drizzle with melted chocolate. Garnish with reserved cherries. Store in refrigerator.