In a large bowl, blend the ricotta, the squaquerone, the Parmigiano-Reggiano, the lemon zest, the pepper, nutmeg and salt to taste. Check the seasoning, stir in the egg yolk, cover and chill 2 hours or overnight before proceeding.
Remove the filling from the refrigerator and let sit at room temperature 10 minutes.
Divide the dough into 3 equally-sized balls and roll them out to the thinnest setting on a pasta rolling machine. Cut each sheet into 2-inch squares. In the center of each square, place tablespoons of the filling. Fold diagonally-opposite corners to meet each other to form the cappelletti. Place the cappelletti on a sheet tray dusted with semolina flour, and cover with clean, damp dish towels or hold in the freezer until ready to use.
Bring the chicken stock to a boil and add salt if necessary. Drop the capellatti in the chicken stock, working in batches if necessary to avoid overcrowding the pot. Cook for 2 minutes, remove from heat and serve immediately with a ladle of the broth spooned over, and topped with grated Parmigiano-Reggiano.
Mound 3 1/2 cups of the flour in the center of a large wooden cutting board. Make a well in the middle of the flour and add the eggs and the olive oil. Using a fork, beat together the eggs and oil and begin to incorporate the flour, starting with the inner rim of the well.
As you expand the well, keep pushing the flour up from the base of the mound to retain the well shape. The dough will come together when half of the flour is incorporated.
Start kneading the dough with both hands, using the palms of your hands. Once you have a cohesive mass, remove the dough from the board and scrape up and discard any leftover bits. Lightly reflour the board and continue kneading for 6 more minutes. The dough should be elastic and a little sticky. Wrap the dough in plastic and allow to rest for 30 minutes at room temperature. Roll or shape as desired.
In a large, heavy-bottomed saucepan, heat the oil over high heat until smoking. Add all the chicken parts and brown all over, stirring to avoid burning. Remove the chicken and reserve. Add the carrots, onions, and celery to the pot and cook until soft and browned. Return the chicken to the pot and add 3 quarts of water, the tomato paste, peppercorns, and parsley. Stir with a wooden spoon to dislodge the browned chicken and vegetables bits from the bottom of the pan. Bring almost to a boil, then reduce heat and cook at a low simmer until reduced by half, about 2 hours, occasionally skimming excess fat. Remove from heat, strain, and press on the solids with the bottom of a ladle to extract out all liquids. Stir the stock to facilitate cooling and set aside. Refrigerate stock in small containers for up to a week or freeze for up to a month.
Recipe copyright 2000, Mario Batali. All Rights Reserved.