Prepare and bake cake according to package
directions, using a greased 13x9-in. baking dish.
Cool on a wire rack 1 hour. In a small bowl,
dissolve gelatin in boiling water; stir in cold
water and set aside.
With a meat fork or wooden skewer, poke holes
about 2 in. apart into cooled cake. Slowly pour
gelatin over cake. Cover and refrigerate.
In a large bowl, whisk milk and pudding mix 2
minutes (mixture will be thick). Fold in whipped
topping. Spread over cake. Decorate with
sprinkles. Cover and refrigerate until serving.