Prepare cake mix according to package directions substituting diet soda for water, oil and eggs. Pour prepared batter into a 13x9-inch baking pan coated with cooking spray. Bake according to package directions.
When cake has cooled, poke holes in cake with a large-tined fork. Mix Jell-O with boiling water until dissolved. Add the cold water, mix well, then pour entire mixture over cake. Refrigerate for at least 2-3 hours.
Combine vanilla pudding mix with milk and vanilla in bowl of an electric mixer. Mix well. Fold in thawed whipped topping and use this mixture to frost cake. Keep cake refrigerated.
Bake, Combine
2007, 2008