Slice ends off zucchini and squash, cut into 1-inch chunks. Pour the olive oil into a large saucepot. Add the zucchini and squash and saute over medium heat. Peel eggplant and cut into 1-inch chunks and add to pot. Saute about 10 to 15 minutes or until it begins to soften. Add onion, garlic, green pepper, mushrooms, tomatoes and tomato sauce. Add the spinach to pot. Season with salt and pepper and add the oregano and basil, use more or less according to taste. Lower heat to low and simmer approximately 1 hour until tender.
In a large bowl combine the ricotta cheese and eggs and mix well. Add the parsley and pepper.
TO ASSEMBLE LASAGNA:
Using a 13"x9" baking dish ladle some of the veggie sauce on the bottom. Place three noodles over the sauce, be careful to leave some space between each noodle as they expand. Spoon approximately half of the ricotta mixture over the noodles. Sprinkle with 1/3 of the mozzarella cheese, then some parmesan cheese. Ladle about 2 cups sauce over the cheeses. Then repeat the process once more reserving about 1 cup of the mozzarella. Place the rest of the noodles on top of the sauce layer and spread more sauce on top. Sprinkle with parmesan cheese and cover with foil.
Bake at 375 degrees F for approx. 45 minutes, then remove foil and add the rest of the mozzarella. Place back in oven for about 10 to 15 minutes or until hot and bubbly.