Prepare cake as directed for 9x13-inch baking pan. Cool 15 minutes. Pierce with large fork all over.
Stir dry gelatin into boiling water until completely dissolved; stir in cold water. Carefully pour over cake. Refrigerate 3 hours.
Tint whipped topping orange with food coloring; spread on top of cake. Refrigerate at least 1 hour. Draw spider web with chocolate glaze. Serves 10–12.
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