Mix up cake mix. Only pour 1/2 of the mix into a greased 9x13" cake pan. (should be thin) discard remaining cake mix, or make cupcakes with remaining batter.
Bake cake as directed, cut the bake time as the cake is thinner
Mix up the gelatin according to directions, chill until soft set.
Pour soft set jellow over cooled cake and refrigerate.
Make up pudding according to direction, cool slightly and pour over set jello/cake.
Top with cool whip and serve.