For the sauce, heat olive oil in a large skillet over medium heat.
Add onions and garlic and cook about 3 minutes, or until onions are translucent.
Add tomato sauce, diced tomatoes, oregano, salt, and pepper.
Bring to a boil, then simmer for 20 minutes stirring occasionally.
Add additional kosher salt to taste.
Meanwhile, place eggs in a small bowl and beat slightly.
In a medium shallow bowl, mix together bread crumbs, Parmesan, oregano, and basil.
Dip eggplant slices in egg and then in bread crumbs.
Place breaded slices on a cookie sheet sprayed with non-stick spray.
Bake slices in a preheated oven at 375 for 15 minutes.
Turn slices over and bake an additional 10 minutes.
Remove from oven and increase heat to 400 degrees.
In a 9x13 casserole dish, place 2 cups sauce in the bottom and half of the baked eggplant.
Cover eggplant with another 2 cups sauce and then 1 cup mozzarella cheese.
Then layer the second half of the baked eggplant, the last 2 cups sauce, and 1 cup mozzarella.
Sprinkle additional grated Parmesan cheese over top if desired.
Bake at 400 for 15 minutes, or until cheese is melted.
Let dish cool 10 minutes before serving.