01 - Preheat your oven to 350°F. Lightly grease a 9x13-inch baking pan.
02 - In a large mixing bowl, combine the white cake mix, 1 cup of water, 1/2 cup of vegetable oil, and 3 large eggs. Beat the mixture with an electric mixer on medium speed for 2 minutes until smooth.
03 - Pour the prepared batter evenly into the greased 9x13-inch baking pan. Bake for 28 to 32 minutes, or until a wooden toothpick inserted into the center of the cake comes out clean.
04 - Allow the baked cake to cool in the pan for 15 minutes.
05 - Using the handle of a wooden spoon, carefully poke holes all over the surface of the cake, spacing them approximately 1 inch apart.
06 - In a medium bowl, dissolve the 3-ounce package of lime-flavored gelatin in 1 cup of boiling water. Stir well until completely dissolved. Then, add 1/2 cup of cold water and stir again.
07 - Slowly and evenly pour the prepared lime gelatin mixture over the entire surface of the poked cake, ensuring it soaks into the holes.
08 - Refrigerate the cake for at least 2 hours, or until it is completely chilled and the gelatin has set.
09 - In a small bowl, gently fold 1 tablespoon of lime zest and the optional 2 tablespoons of powdered sugar into the thawed 8-ounce container of whipped topping.
10 - Spread the lime-infused whipped topping evenly over the thoroughly chilled cake. Garnish with additional lime zest for presentation.
11 - Slice the chilled cake and serve immediately.