1 Cook pasta according to package directions; drain and rinse under cold water until completely cool. Drain thoroughly.2 Preheat oven to 350° F. Squeeze as much water as possible from the thawed spinach3 . In a large bowl, stir together the spinach, mozzarella, ricotta, carrots, egg whites, pepper and nutmeg until thoroughly blended.4 Line the bottom of an 11 x 7-inch baking dish with 1/2 cup tomato sauce.5 ivide the ricotta mixture among the pasta shells, pressing the filling into the shells with spoon to completely fill each shell.6 . Arrange the shells side by side in a baking dish. 7 Coat the shells with an even layer of the remaining tomato sauce. 8 . Sprinkle with Parmesan cheese, if desired.9 Bake until the center of the shells are heated through and the sauce is bubbling, about 40 minutes. Let stand 10 minutes before serving.
