Trim the ends off the eggplant and cut them into 1/4 inch rounds and place them into a large bowl.
Liberally sprinkle 2 tbsp of salt over the eggplant and toss to coat them.
Fill the bowl containing the eggplant rounds with water and press down and swirl the water so some of the eggplant becomes submerged and the water gets salty. Let the eggplant soak for 30 minutes, turning them periodically so the salt distributes into the water.
Pre-heat the oven to 400°F.
Drain the eggplant then rinse them and lay them onto a clean tea towel. Dry both sides of the eggplant.
Rinse and dry the bowl you used to soak the eggplant and place the dried eggplant back into the bowl and sprinkle them with 1/2 tsp of salt, 1/2 tsp of black pepper and drizzle them with 5 tbsp of olive oil. Mix together using your hands until the eggplant rounds are evenly coated with the oil, salt and pepper.
Lay the eggplant onto parchment lined baking sheets, (you may need more than one) and bake them for 30-40 minutes, flipping them halfway through and adding more oil if needed, until they are tender when pierced with a fork.
Add a thin layer of sauce to the bottom of an 11x7 roasting pan, then add one layer of eggplant.
Add a layer of sauce on top of the eggplant, if the sauce is too thick add some water to it. You want a thinner sauce for this.
Add a layer of mozzarella on top of the sauce, then sprinkle it with 1 tbsp of parmesan cheese.
Repeat the process, eggplant, sauce, mozzarella, making sure the top layer is mozzarella. You will only add the parmesan cheese to 1 layer. It's ok to stack some of the eggplant when you are nearing the end.
Cover the pan with aluminum foil and bake 30-40 minutes or until the sauce is bubbling and the cheese is melted.
Add a few basil leaves to the top if desired.