Prepare the cake mix as directed on the box.
Add the 2 tbsp. of lemon zest to the cake mix batter.
Bake the cake mix batter as directed on the box in a 9x13 baking dish.
Remove the cake from the oven, poke holes in the cake 5 in a row by 8 rows, and set it to the side.
In a medium-sized bowl add the pudding mix, milk, and mix until thick.
Gently pour the pudding mix onto the cake, making sure it is evenly spread.
Allow the cake to cool completely.
Prepare the frosting while the cake cools.
In the bowl of a mixer add the cream cheese, powdered sugar, lemon juice, heavy cream and lemon zest.
Mix on medium until well combined.
Begin to frost the cake, if it is completely cooled.
Make sure to spread the frosting over the cake evenly.
Garnish as the cake with sliced lemons and lemon zest if desired.
Enjoy!