Heat a light drizzle of olive oil in a Dutch oven over medium heat. Add the chicken thighs and sear for about 10 minutes per side until the skin is golden. Pour off the excess rendered fat.
2
Cut the carrots and celery into large pieces and quarter the onion. Set aside.
3
Add about 1 tablespoon of extra virgin olive oil to the pot and stir in the vegetables for a few seconds until fragrant.
4
Add plenty of water, a good pinch of salt, and parsley stems. Return the chicken to the pot, reduce to a gentle simmer, cover, and cook for about 2 hours until the chicken is very tender.
5
After 2 hours, remove the chicken and vegetables from the broth. Shred the chicken meat into small pieces. The broth should be clear and beautifully golden.
6
For the meatballs, rehydrate the breadcrumbs in milk. Add the ground beef, egg, grated garlic, chopped parsley, Parmesan, salt, and pepper. Mix until combined.
7
Roll the mixture into very small meatballs, which takes about 20 minutes. Drop them directly into the simmering broth or place on a plate first.
8
Add the shredded chicken to the broth with the meatballs and simmer for about 45 minutes.
9
Thoroughly clean the escarole by rinsing it well to remove any sand, chop it, and add it to the broth. Simmer for about 20 minutes until wilted.
10
Whisk together 2 eggs with about 1/4 cup freshly grated Parmesan and black pepper. Do not add salt as the soup is already well-seasoned.
11
Bring the soup to a high heat. Slowly add some hot broth to the egg mixture, then pour the mixture back into the soup pot in a thin stream to create egg ribbons. Simmer for about 2 minutes until set and finished.