yeah boil the shells for 15 minutes until soft, then remove the shells place shells on a plate. Grab 4 0r 5 spinach make sure to wash leaves repeately until there are no pebbles in the leaves, than finely chop spinach chop two cloves of garlic heat a 1 inch pan with 2 tablespoons of canola oil and when pan is hot put spinach first let it fry for a few minutes than quickly add the garlic and fry for another few minutes. Then get one cup of milk and heat in large pan, when milk is ready pour in with the spinach and garlic and cook for15 minutes. Then stuff shells and you chould fry the shells in a little bit of oil or you could just heat and then serve .                                                                                                                   ingredients     1 cup milk  4 spinach leaves 2 cloves of garlic  2 tablespoons oil and 8 jumbo shells. 

http://www.bettycrocker.com/recipes.aspx/spinach-manicotti/aa249c1f-61f1-4fe5-85d7-2c34db5b714e

Spinach Manicotti
From Betty Crocker

1 box (8 oz) uncooked manicotti shells (14 shells)
2 cups shredded Italian cheese blend (8 oz)
1/4 teaspoon crushed red pepper flakes
1 container (15 oz) ricotta cheese
1 box (10 oz) Cascadian Farm frozen organic cut spinach, thawed, drained, squeezed dry
2 cloves garlic, finely chopped
1 egg, slightly beaten
1 jar (25.5 oz) Muir Glen pasta sauce (any flavor)

1. Heat oven to 375°F. Cook manicotti as directed on box. Rinse with cool water; drain well.
2. In medium bowl, stir together 1 1/2 cups of the Italian cheese blend, the red pepper, ricotta cheese, spinach, garlic and egg.
3. In bottom of ungreased 13x9-inch (3-quart) glass baking dish, spread 1 cup of the pasta sauce. Spoon ricotta mixture into manicotti; place over sauce in dish. Pour remaining sauce over manicotti.
4. Cover tightly with foil; bake about 30 minutes or until sauce is bubbling. Uncover dish; sprinkle with remaining 1/2 cup Italian cheese blend. Bake uncovered 5 minutes longer or until cheese is melted.

Substitution: The Italian cheese blend adds a nice flavor twist to this dish, but you could use mozzarella instead.

Do-Ahead: You can make this recipe up to 24 hours ahead. Just cover and refrigerate until ready to bake. You can expect about 15 minutes extra baking time.

You could omit the chicken from this one:

Chicken and Spinach Stuffed Shells
From Betty Crocker Most Requested Recipes

18 large pasta shells (from 16-oz package)
1 container (15 oz) whole-milk ricotta cheese
1 egg, slightly beaten
1/4 cup grated Parmesan cheese
2 cups frozen cut leaf spinach, thawed, squeezed to drain
1 cup chopped deli rotisserie chicken (from 2- to 2½-lb chicken)
1 jar (26 oz) tomato pasta sauce
2 cups shredded Italian cheese blend (8 oz)

1. Heat oven to 350°F. Cook and drain pasta as directed on package. Rinse with cool water; drain.
2. Meanwhile, in medium bowl, mix ricotta cheese, egg, Parmesan cheese, spinach and chicken.
3. Spread 1 cup of the pasta sauce in bottom of 13x9-inch (3-quart) glass baking dish. Spoon about 2 tablespoons ricotta mixture into each pasta shell. Arrange shells, filled sides up, on sauce in baking dish. Spoon remaining sauce over stuffed shells.
4. Cover dish with foil; bake 30 minutes. Sprinkle with Italian cheese blend. Bake uncovered 5 to 10 minutes longer or until cheese is melted.

Success Hint: Thaw the spinach overnight in the refrigerator or microwave about 2 minutes or just until thawed.