In a pot of salted boiling water, cook the orzo according to the directions on the package. Once cooked drain well and set aside.
In a pot, heat the olive oil over medium heat. Sauté the onion, celery, and carrots for about 4 minutes. Add in the chicken, season with salt and pepper, and sauté for 2 to 3 minutes more. Pour in the broth, cover with a lid and bring to a simmer for 20 minutes.
Slowly pour in the egg while whisking the soup in a circular motion to prevent the egg from clumping up. Add the spinach and simmer for another 2 to 3 minutes.
Notes
Adjust the portions to batch cook for later in the week