Microwave chocolate and cream in large microwaveable bowl on MEDIUM (50%) 2 to 3 min. or until chocolate is completely melted and mixture is well blended, stirring after 1-1/2 min. Cool slightly. Gradually add powdered sugar, beating with electric mixer on high speed until mixture is well blended and of desired spreading consistency.
Use a serrated knife to cut off top one third of cake. Set top aside.
Place bottom of cake on large serving platter; spread with chocolate frosting. Scatter candies and some of the coins around cake as desired. Replace top of cake; spread with the remaining chocolate frosting to resemble a treasure chest.
Decorate top of chest with string licorice and some of the remaining candies.
Sprinkle wafer crumbs onto platter to resemble sand. Arrange any remaining coins and candy in "sand." Store in refrigerator.
