In a large bowl, mix together the ricotta, stracchino, Parmigiano Reggiano, nutmeg, lemon zest, and egg until thoroughly combined.
On a clean work surface lightly dusted with flour, roll out the pasta dough into an 18-inch circle 1/8 inch thick. Spread a thin layer of the cheese filling over the bottom half of the dough. Fold the top half of the dough over the filling to form a half moon. With a handheld pasta cutter, cut the dough into long vertical strips 1/2 inch wide. Then cut horizontally every 1/4 inch to make small rectangles.
Place the stuffed pillows on a lightly floured sheet pan. Place in the freezer at least 1 hour prior to cooking.
In a 6-quart pot, bring the chicken broth up to a boil. Add 2 Tbs. salt. Drop the pasta into the broth and gently simmer until tender. Ladle the soup into shallow bowls and serve with pepper and grated Parmigiano Reggiano.
Photo: Melissa Pellegrino & Matthew Scialabba