Peel the eggplant and slice into ½ inch thick slices. Lay the sliced eggplant on a rack over a baking sheet and heavily salt both sides of the eggplant with kosher salt. Let the eggplant sit for at least 15 minutes and up to an hour. After the eggplant sits, run the slices under water to rinse away the salt and pat the eggplant dry.
Set up 3 shallow dishes in which to prepare the breading station for the eggplant. In the first dish, mix the flour with a ½ teaspoon each of salt and garlic powder. In the second dish, whisk the egg with 2 tablespoons of water and a pinch of salt. In the final dish, combine the panko, ⅓ cup parmesan cheese, remaining ½ teaspoon garlic powder, a pinch of salt, oregano, and red pepper flakes.
Dredge each slice of the eggplant in the four mixture, shaking off the excess. Then dip into the egg mixture, allowing the excess egg mixture to drip off the eggplant. Finally, coat the eggplant slices in the breadcrumb mixture, pressing to adhere the breading to the eggplant.
Spray the breaded eggplant with cooking spray and then place it sprayed side down into the basket or tray of the air fryer. Be careful to not overlap the eggplant, so that it cooks and browns evenly. Spray the top of the eggplant slices with cooking spray.
Air fry at 370 degrees F for 6 minutes. After 6 minutes, remove the basket, flip the eggplant, spray again with cooking spray and return back to the air fryer and cook for an additional 6 minutes at 370 degrees F.
Remove the basket and top each slice of eggplant with 1-2 tablespoons of tomato sauce and a slice of mozzarella cheese, or 2 tablespoons of shredded mozzarella cheese, and a couple teaspoons of parmesan cheese.
Return the air fryer, and air fry for 3-4 minutes at 370 degrees F, or until the cheese is melted and browned.
Doubling the Recipe: You can double this recipe but you will need to work in batches, so you don't overcrowd your air fryer. If you need to prepare the eggplant in batches, place the uncooked breaded eggplant in the refrigerator while the first batch is in the air fryer. Once the first batch has been cooked through, place the cooked eggplant parmesan on a sheet pan and hold warm in a 200-degree oven.Storage: Store leftover eggplant parmesan in an airtight container for up to 3 days in the refrigerator. To reheat, air fry the eggplant for 3 minutes at 360 degrees, or until warmed through.Crushed Red Pepper Flakes: Feel free to omit if you are sensitive to spice.