Slice eggplants into ¼-inch thick rounds. Lay them on paper towels and sprinkle both sides generously with salt. Let them sit for 30 minutes.

Preheat your oven to 400°F. Arrange eggplant slices on baking sheets lined with parchment paper. Brush both sides lightly with olive oil. Roast for 20-25 minutes, flipping halfway through.

Combine ricotta cheese, half the Parmesan, garlic powder, and fresh basil in a medium bowl. Mix well and set aside.

Reduce oven temperature to 375°F. Spread 1 cup of marinara sauce across the bottom of a 9x13-inch baking dish. Layer one-third of the roasted eggplant slices over the sauce. Dollop one-third of the ricotta mixture over the eggplant, then sprinkle with 1 cup mozzarella. Repeat these layers twice more.

Pour the remaining marinara sauce over the final eggplant layer. Top with remaining mozzarella and Parmesan. If using breadcrumbs, sprinkle them over the cheese.

Cover the dish with aluminum foil and bake for 30 minutes. Remove the foil and bake an additional 15-20 minutes until the cheese bubbles and turns golden brown. Let the casserole rest for 10 minutes before serving.