For meatballs: In a medium bowl whisk together egg, bread crumbs, milk, nutmeg, and 1/8 tsp. each salt and black pepper. Stir in pork, chopped parsley, and Parmesan.
In a 5- to 6-qt. Dutch oven heat oil over medium-high heat. Add celery and onion; cook and stir 5 minutes or until tender. Add escarole, chicken broth, 2 cups water, and whole parsley leaves. Bring to boiling; reduce heat to simmer.
Drop rounded tablespoons of pork mixture into broth. Gently stir meatballs in broth. Cover; simmer 10 minutes or until meatballs are cooked through (160 degrees F). Top with additional Parmesan and black pepper. *Tip: Another night, shape and bake these meatballs on a pan lined with foil in a 375 degrees F oven for 18 to 20 minutes or until internal temperature reaches 160 degrees F. Serve over pasta with pesto or tomato sauce.