Preheat your oven and prepare the white cake mix as directed on the box. Pour the batter into a 9x13 baking pan and bake as directed.
Once the cake is baked, let it cool for about 15 minutes. Then, use a fork to poke holes all over the cake.
In a mixing bowl, combine the boiling water and Jell-O gelatin mix. Stir until the gelatin is completely dissolved. Add the cold water and mix well.
Pour the Jell-O mixture evenly over the cake, making sure it gets into the holes. Refrigerate the cake for at least 3 hours or until the Jell-O is set.
Spread the whipped topping evenly over the cake. Slice and serve chilled.