Preheat oven to 350 degrees.
Thinly slice 2 scallions. Defrost chopped spinach (Use a kitchen towel to squeeze out all excess moisture)
Combine all ingredients except the manicotti shells and pasta sauce in a large mixing bowl.
Using a spoon or clean hands, divide the filling among the 12 manicotti shells. (If freezing shells for a future use, you are now ready to transfer the stuffed shells to the freezer.)
Spread 1 cup of the pasta sauce onto the bottom of a 13×9 inch baking dish to prevent noodles from sticking. Arrange the shells in dish. Top with remaining pasta sauce.
Sprinkle with additional mozzarella cheese to your preference (I use about ¼ cup). Cover dish with foil and bake at 350 degrees for 40 minutes. Remove foil and bake for an additional 10 minutes, until cheese is hot and bubbly. Allow manicotti to cool for about 5 minutes. Serve and enjoy