Cut the eggplant into roughly 1/4 inch thick round slices and arrange over sheets of paper towel. You want the paper towel on each side of the eggplant.
Sprinkle each side with a little salt to draw out the liquid. Let rest for 45-60 minutes. Press down with the paper towel at the end to soak up any remaining surface moisture. Paper towels will become noticeably saturated/transparent. This step is critical—do not skip it!
Preheat the oven to 350°F.
Combine breadcrumbs, 1/2 cup of parmesan cheese, and fresh herbs, on a plate and set aside. In a small bowl, whisk the eggs and water and set aside. On another plate, spread the flour.
Coat the eggplant with the flour and shake off the excess. Dip in the egg (let excess drip), and then fully coat with the breadcrumb mixture, patting with your fingers to ensure the breadcrumbs adhere. Repeat with all slices and set aside until ready to fry.
Heat the olive oil in a 12-inch cast iron skillet over medium heat. You want enough oil to cover the bottom of the pan by 1/4+ inch. Add the eggplant in batches and sauté until golden brown and crispy (about 30-45 seconds per side). Remove the eggplant and place it on a baking sheet to rest until the next step. The eggplant may brown faster as the oil continues to heat. You may need to add more oil halfway as it's absorbed.
Turn off the heat and let the skillet cool for about 5 minutes. Use a paper towel to give the skillet a quick wipe, soaking up any excess oil and burnt chunks from the eggplant.
Layer the bottom of the skillet with 1 cup of tomato sauce. Add a layer of eggplant, filling as much of the bottom of the pan as possible with no overlap. Top with a 1/2 cup of marinara, then 1/4 cup parmesan cheese, and 1 cup mozzarella cheese. You can cut the eggplant in half around the perimeter so it fits more snugly if you prefer.
Repeat by creating the second layer starting with eggplant, 1/2 cup of tomato sauce, 1/4 cup of parmesan, and finish with 1 cup of mozzarella cheese.
Place in the oven and bake uncovered for 25-30 minutes or until cheese starts to bubble and slightly brown on the top. You can finish with a quick broil at the very end for a little charred cheese if you prefer, just note it will brown FAST. Let cool for 5 minutes, garnish with fresh basil and parsley if desired, and serve with pasta if desired.