Sautee chopped onions and mushrooms until tender. Steam chopped spinach until wilted (or use thawed frozen spinach). Combine ricotta, mozzarella, 3/4 cup of the Parmesan, eggs, parsley, spices. Add spinach and 3/4 of sautee to mixture. Fill uncooked manicotti shells; place filled shells in a single layer in a greased 13x9 baking pan. Add remaining sautee to spaghetti sauce. Cover manicotti with sauce. Sprinkle with remaining Parmesan. Bake at 350 F for 35 minutes. This is probably my favorite Italian dish. Recipe By :