Chicken and Dumplings

Name: Chicken and Dumplings
Ingredients: 1 pound ricotta; 1 /2 cup plus 2 tablespoons all-purpose flour plus more; 1 large egg, beaten to blend; 1 1/4 cups finely grated Parmesan; 3 /4 teaspoons freshly grated nutmeg; 1 /2 tablespoon kosher salt; 10 cups low-salt chicken broth; 2 pounds skinless, boneless chicken thighs; 1 /4 cup (1/2 stick) unsalted butter; 6 tablespoons all-purpose flour; 2 celery stalks, cut crosswise into 1/4'-thick slices; 1 carrot, peeled, thinly sliced; 1 parsnip, peeled, cut into 1/4'; 1 leek, halved lengthwise, cut crosswise into 1/4'-thick slices; 1 /4 cup chopped flat-leaf parsley; 1 /4 cup chopped fresh chives; Kosher salt, freshly ground pepper; Shaved Parmesan