1. Preheat oven to 350 degrees. Cook manicotti according to package directions and rinse in cold water.
2. In a medium-size bowl combine ricotta, one cup of mozzarella cheese, Parmesan cheese, spinach, Italian seasoning and egg.
3. Stuff the shells with the cheese mixture. Using a pipe bag works well. I just use my hands.
4. In a 9x13 in pan add 1 cup of sauce to the bottom of the pan. Line the manicotti in an even layer. Cover with remaining sauce and cheese. Bake for 25 to 30 minutes or until cheese is melted and bubbly.