See spaghetti sauce recipe for the sauce.
Prepare the chopped spinach according to directions. Cook however much you would like in your filling but I usually cook about a quarter of a package. Drain and let cool.
In a bowl mix ricotta, egg and parmesan cheese. Add spinach a little at a time until you are satisfied.
Using a rectangular pan that is fairly deep, start your layering. Put a thin layer of sauce on the bottom of the pan. Lay lasagna noodles over the sauce. Spoon the ricotta mix on the noodles and spread as best you can. Sprinkle shredded mozzarella cheese over the top. Lay another layer of noodles on top. Spoon sauce over the top. Add another layer of noodles, then spread the ricotta mixture over the noodles. Add another layer of mozzarella cheese and top with noodles. Cover with sauce.
If you have more ricotta mix, you can add another layer but be careful of over filling the pan.
After the last layer of sauce, sprinkle mozzarella cheese over the top, then sprinkle parmesan cheese on top.
Put in a 325º oven and cook for about an hour. The sauce should be bubbling at the side.
Remove from the oven and let stand for about 10 minutes.
Serve with garlic bread and salad.