1 teaspoon kosher or sea salt, plus extra to taste
Freshly ground black pepper, to taste
2 quarts (8 cups) low-sodium chicken stock
2 large carrots, trimmed, peeled, and cut into 1/4-inch dice
1 cup penne pasta
5 cups white Swiss chard (or escarole), stems trimmed, washed, and coarsely chopped
1 cup shredded mozzarella
Garnish: finely shredded Parmesan cheese
In a medium bowl, whisk egg and water together until well blended. Add turkey, breadcrumbs, cheese, parsley, garlic, salt, and pepper. Using moistened hands, shape turkey mixture into 1-1/4-inch meatballs. Place on a baking sheet; chill 30 minutes.
In a large pot, bring chicken stock to a boil. Reduce heat to medium and add carrots and turkey meatballs; simmer uncovered 8 minutes. Add pasta and cook until al dente (slightly undercooked), about 3 minutes.
Stir in Swiss chard and simmer until tender, about 3 to 5 minutes longer. Season soup to taste with salt and pepper.
Divide mozzarella into six serving bowls and ladle soup into bowls. Garnish with additional Parmesan cheese.