1. Bring 2.5 litres of water to a boil and drop the lasagna noodles inside one by one.
2. Stir gently to make sure they don't stick together and boil for 12 minutes.
3. Drain the noodles and immediately cool them down in iced water for 1 minute.
4. In a mixing bowl combine the spinach, ricotta cheese, egg and garlic powder, and season to taste.
5. Spread the filling over the lasagna noodles, leaving about 1/2" at the end not covered, and roll them.
6. Spread 1 cup of tomato sauce on the bottom of a baking dish and arrange the manicotti with the edge of the rolled noodle facing down.
(Alternatively, you could use the manicotti tubes, on the right side of this page).
7. Spread the rest of the tomato sauce over the manicotti and bake them in a preheated oven at 450 F, until they are soft and the sauce becomes thick.
8. Sprinkle the Parmesan cheese over the manicotti and cook for 3 minutes more.
The leftover manicotti can be wrapped in cling wrap and frozen for whenever you need a quick lunch.