How to Make It
Mix the veal, egg, Parmesan, and a pinch of salt in a bowl. Take a little mixture at a time and form small balls.
Pour about 2 cups (500 milliliters) of the stock into a saucepan, bring to a boil, reduce the heat to a simmer. Add the meatballs and cook for a few minutes. Drain and set aside.
Bring the remaining 10 cups (2.5 liters) stock to a boil in a saucepan. Add the potatoes, celery, carrots, and onion and cook for 3 – 4 minutes. Add the escarole and cook for 3 – 4 minutes. Remove from the heat and set aside.
Divide the meatballs and mozzarella among 6 bowls. Ladle the vegetable stock over everything. Serve sprinkled with grated Parmesan.