Freeze cake in pan for 30 minutes to firm top. Spread ice cream in an even layer to the top edge of pan. Freeze several hours until ice cream is firm.
Remove sides of pan. Frost sides of cake and a 1-inch border around cake top. Return to freezer if ice cream softens.
Squeeze decorating icing in a crisscross pattern on top. Press sugar sticks diagonally around sides (if using candy canes remove bent tips). Place cherries around top of cake. Freeze several hours or overnight before serving.
Dampen top and sides of marshmallows with water. Roll in sugar crystals. Insert pretzel sticks to make 'drumsticks'. Place on top of cake before serving.