Just read the ingredients before you toss it away! Doesn't tast "diet" at all.
1 lemon cake mix
12 oz of diet lemon-lime soda (sprite works best i think)
Combine cake mix and soda. Pour batter into a 9x13 greased baking pan. Bake at 350 for 30-35 min. Wait for cake to cool and poke random holes in it with the back of a wooden spoon.
1 large box of instant vanilla pudding (fat free/sugar free for diet but you can use regular)
2 cups milk (skim for the diet version)
1/2 of small tub fat free/sugar free whipped topping (I think cool whip tastes the best)
Mix all ingredients until creamy and pour over cake. Put in refrigerator until the pudding is set. Top with remaining whipped cream.
You want diet chocolate? You got it. Just substitute the following:
Devils Food cake mix
Diet vanilla or cherry cola
Instant chocolate pudding
Garnish with chocolate shavings on top of the whipped topping.