Arrange eggplant slices in a single layer on a wire rack set over a baking sheet. Sprinkle both sides with kosher salt and let stand for 30 minutes until moisture beads on the surface.

Pat each slice completely dry with paper towels. The slices should feel noticeably firmer and less spongy.

Heat the oven to 220 C / 425 F. Line two large baking sheets with wire racks and lightly spray the racks with olive oil.

In a shallow bowl, combine panko, 20 g of the Parmigiano, dried oregano, garlic powder, and black pepper. Stir to mix evenly.

Dip each eggplant slice in beaten egg, letting excess drip off, then press firmly into the panko mixture on both sides until coated.

Place coated slices in a single layer on the prepared wire racks. Mist the tops lightly with olive oil spray.

Bake for 18 to 20 minutes, flipping once at the 10-minute mark, until slices are golden and crispy on both sides. Remove from oven and reduce heat to 190 C / 375 F.

Spread a thin layer of marinara (about 80 ml) across the bottom of a 23 x 33 cm baking dish.

Lay half the baked eggplant slices over the sauce in a single layer. Spoon over half the remaining marinara, scatter half the mozzarella, a few basil leaves, and 10 g Parmigiano.

Repeat with remaining eggplant slices, remaining marinara, remaining mozzarella, and remaining Parmigiano. Add red pepper flakes if using.

Bake uncovered at 190 C / 375 F for 15 minutes until the cheese is melted and the edges bubble. For a browned top, switch to the broiler for the final 2 minutes, watching closely.

Let the dish rest for 5 minutes before slicing. Top with fresh basil leaves before serving.