Make the yellow cake mix according to package instructions. Bake in a 9x13 inch pan for 30-35 minutes.
Once baked, remove from oven and immediately make several holes on top of the cake using a fork.
Boil 1.5 cups of water and mix in the gelatin. Pour the mixture over cake right away. Put the pan in the fridge for at least one hour.
After one hour, mix the pudding with the cold milk and pour it over the cake. Put the cake back into the fridge to set.
Spread the whipped topping on top before serving.
