Preheat oven to 400 degrees F. Slice the eggplant into 1/4″ rounds. Place on a baking tray and sprinkle with salt. Place another baking tray on top, and place a heavy pot or book on top to add weight. After 30 minutes, rinse the eggplant. Drizzle with olive oil and bake for 30 minutes until golden.
Prepare the Sauce:
Chop onion and saute in olive oil until golden brown. Puree the tomatoes and add to onions, with salt and pepper. Cook on low heat, uncovered for about 30 minutes until reduced.
Prepare the Ricotta Mixture:
In a large bowl, mix eggs into ricotta, add the mozzarella, the Parmigiano and the salt and pepper.
Assemble the Lasagna:
Bring a large pot of salted water to a boil. Cook the lasagna for half of the suggested package cooking time (about 4 or 5 minutes), drain and set aside. (Drizzle with oil to prevent sticking.)
Coat the bottom of a bake-proof pan (9 x 11 or other similar size at least 3″ deep) with a sauce.
A layer of lasagna (slightly overlapping), a layer of the ricotta mixture, about 1/3 of the eggplant; a few spoons of sauce. Repeat layers until you reach the the top of the pan. (Depending on the depth and size of the pan, you may have left over lasagna, or you can make more layers with slightly less filling between layers.) If quantity allows, cover top with a layer of lasagna, and some sauce and a generous sprinkle of Parmigiano.
Cover with aluminum foil and cook at 350 for 30 minutes. Remove foil and cook for 10-15 more minutes until top is browned. Remove from oven and let rest for 10 minutes before serving.