Preheat oven to 375 degrees.
In a medium size skillet, brown ground beef.
In separate skillet, brown Italian sausage (the sausage cooks more quickly than the beef). Drain excess grease out of both and combine.
In large pot, pour in both jars of sauce. Pour all meat into sauce and simmer for 20 to 30 minutes so flavors combine well.
In separate pot, cook pasta noodles (follow package directions). Set aside and let cool.
In medium size bowl combine: eggs, ricotta cheese, 2 cups mozzarella, and Italian seasoning. Set aside.
In your casserole dish, pour 1/2 cup pasta sauce on the bottom surface of the dish and spread so that there are no dry spots on the bottom of your pan. Spread 3 to 4 noodles across dish. Cover noodles with sauce and meat mixture. Place spinach over sauce.
Next, use a spoon to place 3 to 4 spoonfuls of cheese mixture along each row of noodles. Cover cheese with noodles. Repeat process until the 12 noodles have all been used. When the last layer is complete, you can finish by placing the remaining 1 cup mozzarella over the top.
Place foil over casserole dish and place in oven for 40 minutes. When only five minutes remain, remove foil and sprinkle parmesan cheese over mozzarella. Return lasagna dish into oven without foil and cook for the remaining 5 minutes.