Make the cake according to the instructions on the box, and cook in two square pans.
While the cake is cooking, cut the lemon into thin slices and set these slices on a paper towel and place a second paper towel over the top to let them dry out a little.
Once the cakes have cooled, transfer one of the cakes to a plate.
Prepare the pudding mix according to the instructions on the box, but only allow it to set for about five minutes.
Poke holes into the cake on the plate, leaving approximately 1" between each hole.
Note: do not poke through to the bottom, make sure your holes go no deeper than halfway into the cake.
Next, pour 1/2 of the lemon pudding onto the cake on the plate, starting in the middle and working your way out.
After this is done, place the second cake on top.
Using your can of whipped cream, make a border around the top of the cake.
Pour the remaining pudding onto the top, again starting in the middle, and work your way out to the border.
Refrigerate for approximately 10 minutes.
Remove from refrigerator and cover the rest of the cake (including the sides and putting it over the pudding) with whipped topping.
Using a butter knife, trace the knife through the pudding and whipped topping to create a marbled design on the top of the cake.
Lastly, place your lemon slices along the sides of the cake as decorations.
You can use any additional slices to decorate the top of the cake.
Keep entire cake refrigerated until ready to serve.
Enjoy!