Preheat your oven to 350°F (175°C).
Prepare a 9x13 inch baking pan by greasing it lightly.
Mix the cake mix, eggs, and water in a bowl until well combined.
Pour the batter into the prepared pan and bake for 30 minutes.
Remove the cake and allow it to cool for 10 minutes.
Using a fork, poke holes all over the top of the cake.
In a separate bowl, dissolve the jello in boiling water.
Add cold water to the jello mixture and stir well.
Pour the jello over the poked cake, ensuring it seeps into the holes.
Refrigerate the cake for at least 2 hours to allow the jello to set.
Spread whipped topping over the cooled cake and garnish with nuts if desired.