Preheat oven to 375 degrees.
Peel and thinly slice the eggplant (about ¼ inch thick). Salt the slices by laying them out on a tea towel or paper towels and sprinkling them with salt. Set the eggplant aside for about half an hour. Lightly pat the moisture off the outside of the slices when the half hour is up.
Lightly oil a 9" x 13" baking pan. Place a thin layer of onions in the bottom of the pan, then top with a layer of noodles. 3 noodles should cover the length of the pan.
Next, add a single layer of sliced tomato and sliced eggplant, half of the shredded cheese and 1/2 tablespoon of Italian seasoning. Repeat, starting with the onions and noodles, then adding the tomatoes, eggplant, cheese and Italian seasoning.
Cover the baking dish with foil. Bake for 45 minutes in a 375 degree oven.
Allow the casserole to cool slightly before cutting and serving. Enjoy!