Preheat your oven to 350 degrees Fahrenheit.
In a large bowl, combine the cake mix and instant pudding mix. Whisk to combine.
Add ¾ cup water, ½ cup vegetable oil, 4 eggs, and ½ tsp vanilla into the dry ingredients. Whisk until fully combined and smooth
Spray a 9x13 inch pan with nonstick spray. Pour the batter into the prepared pan.
Place the pan in the oven and bake according to the package instructions (for me, it was about 30 minutes of cooking time) until the cake is done (a toothpick inserted into the center comes out clean).
While the cake is baking, make the lemon glaze. In a small bowl, combine ⅓ cup freshly squeezed lemon juice with 2 cups powdered sugar and whisk to combine until smooth.
When the cake is done cooking, remove it from the oven. Use a fork to poke little holes into the top of the cake.
Pour the lemon glaze over the top of the warm cake. Then allow the cake to cool at room temperature or in the fridge until cooled completely.
Once cooled, spread the cool whip over the top of the cake. Zest the lemon onto the cool whip. Serve and enjoy!