01 - Preheat oven to 400°F. Line two large baking sheets with parchment paper or lightly grease them.
02 - Arrange eggplant slices in a single layer. Sprinkle both sides lightly with salt and let sit for 20 minutes to draw out moisture and bitterness. Rinse and pat dry thoroughly with paper towels.
03 - Prepare three shallow bowls: Bowl 1 with flour, Bowl 2 with whisked eggs and milk, and Bowl 3 with mixed breadcrumbs, 1 cup Parmesan, oregano, and black pepper.
04 - Dredge each eggplant slice in flour, dip in egg mixture, then coat thoroughly in breadcrumb mixture.
05 - Arrange coated eggplant slices on prepared baking sheets. Brush or drizzle with olive oil. Bake for 25 minutes, flipping halfway, until golden and crisp.
06 - Reduce oven temperature to 375°F.
07 - In a 9x13-inch baking dish, spread a thin layer of marinara sauce. Layer half the baked eggplant over the sauce. Spoon more marinara over eggplant, sprinkle with half the mozzarella. Repeat with remaining eggplant, sauce, and mozzarella. Top with 1/2 cup Parmesan.
08 - Bake uncovered for 25 minutes, until cheese is melted and sauce is bubbling.
09 - Let rest 10 minutes before slicing. Garnish with fresh basil if desired.