Preheat oven to In bowl, combine beaten eggs, ricotta cheese and TWO cups of the mozzarella cheese, spinach and parmesan. Set aside. In a 13X9X3 pan, spread 1 cup of sauce on bottom of pan. Layer in the order, 4 uncooked lasagna noodles (they will overlap), then 1/3 part of the ricotta cheese mixture, half the browned meat, if using, 1 cup mozzarella cheese, and 1 cup of spaghetti sauce. Next layer, 4 uncooked lasagna noodles, 1/3 part of the ricotta cheese mixture, and 1 1/2 c. sauce. Next layer, 4 uncooked lasagna noodles, remaining ricotta mixture and remaining meat, if using, then 1 cup of sauce. For top layer, 4 uncooked lasagna noodles, remaining sauce, and remaining 1 cup mozzarella. Bake covered with foil for 50-60 minutes. Uncover and continue cooking until all the cheese is melted on the top (about 5 minutes). Let stand 15 minutes before serving. If you are using a 13X9X2 pan---just make 3 layers to avoid boiling over.