Preheat oven to 350.
Cook the pasta shells according to package directions, drain and let cool.
In a large skillet, cook the sausage until done, and in crumbles. Let it cool.
In a large bowl, combine the spinach, ricotta, eggs, mozzarella, garlic powder and seasonings.
Add the cooled sausage crumbles.
Add a cup of the pasta sauce to the bottom of a large baking dish (or two smaller ones if you are freezing one).
Fill the shells with the mixture, and place (filling side up) in the dish.
Drizzle remaining marinara sauce over the shells.
Sprinkle with cheese.
Bake for 30 minutes, and serve.