Preheat oven to 350 degrees.
Slice eggplant into approximately 1/8 thick slices lengthwise. Set slices on wire baking rack(s) and sprinkle with kosher salt on each side. Let sit for about 20 minutes or up to an hour to let water come out of the eggplant.
In a small bowl, mix together ricotta, egg, fresh chopped basil and season with salt and pepper until the egg is well combined.
Take a paper towel and pat down eggplant slices to remove excess water.
In a baking dish, add in a thin layer of sauce. Top with one layer of the eggplant (about 3 slices). Top the eggplant layer with about 1/3 of your ricotta mixture, another 1/3 mozzarella, and sauce. Repeat this step 2 more times. Sprinkle the parmesan cheese on the very top.
Cover the baking dish with aluminum foil and bake for 30 minutes. Carefully remove the aluminum foil and bake uncovered for another 20-30 minutes.
Let cool for a few minutes before serving!