Bring Chicken Stock (8 cup), to a boil over high heat and add Arborio Rice (1 cup).
Reduce heat to medium and simmer for 20 minutes, stirring often.
Meanwhile, whisk Egg (4), and Lemon (2), together in a bowl until frothy.
While whisking, slowly add one ladle of the soup at a time to the egg and lemon mixture to temper the mixture.
Transfer the tempered egg lemon mixture to the pot of soup, stirring to combine.
Add Shredded Chicken (to taste) to the soup at this point (if using), and cook another few minutes.
Season with Salt (to taste), Ground Black Pepper (to taste), cut a wedge out of the Lemon (1) to be squeezed for extra lemony flavor, if desired.