In a large mixing bowl, combine ground chicken, breadcrumbs, 2 teaspoons of lemon zest, 2 tablespoons of finely grated parmesan, minced garlic, and a pinch of kosher salt and pepper. Mix well until all ingredients are evenly incorporated.

Form the mixture into small meatballs, about 1-inch in diameter, and set aside.

Heat olive oil in a large soup pot over medium heat. Add diced sweet onion and celery stalks, and saute until softened, about 5 minutes.

Add the parmesan rind to the pot along with the chicken broth. Bring to a simmer.

Once the broth is simmering, gently add the prepared chicken meatballs to the pot. Let them cook for about 5-7 minutes, or until they are cooked through.

Stir in the frozen spinach, diced carrots, and tiny cut pasta. Let the soup simmer for another 10-12 minutes, or until the pasta is tender and the vegetables are cooked.

In a small bowl, whisk together the egg and freshly squeezed lemon juice. Slowly pour this mixture into the simmering soup, stirring constantly to create delicate ribbons of egg.

Taste the soup and adjust seasoning with salt and pepper if necessary.

Ladle the lemon chicken meatball soup into serving bowls.

Garnish each serving with extra lemon zest and grated parmesan cheese.

Serve hot with lemon wedges on the side for an extra burst of citrus flavor.