Wash and slice the eggplant into 3/8 inch slices. Sprinkle salt over the sliced eggplant on both sides. Allow eggplant to rest for about an hour to let the excess water in the eggplant to be pulled out via the salt. Pat eggplant dry with paper towels at the end of the hour to remove excess water and salt.
While eggplant is resting you can make the sauce. In a medium-size saucepan over medium heat combine oil, onions, and garlic. Cook until the onions have become translucent. Add stewed tomatoes and Italian seasoning and stir. Reduce heat to low and allow to simmer.
Preheat oven to 375 and begin breading eggplant. Create an egg wash by whisking together 3 eggs. Dropped sliced eggplant into the egg wash, then flour, and place on a wire rack for it to "dry". Once you have placed the flour layer on the eggplant, repeat with another coating of egg wash, and then dredge in breadcrumbs.
Place the breaded eggplant back on the wire rack. Cook eggplant by placing about 1/4 cup of cooking oil in the bottom of a large skillet over medium-high heat. Place eggplant a few at a time in the skillet. Be careful not to overcrowd the eggplant. Cook for a couple of minutes on each side, cook until golden brown on both sides. Allow eggplant to drain on a wire rack. Place cooked eggplant in a baking dish, top each piece of eggplant with some Parmesan cheese.
Ladle some sauce over each piece of eggplant. If you have plenty of eggplant you may want to make another layer of eggplant, Parmesan cheese, and sauce. Top with Mozzarella cheese and then bake until the cheese has melted.