Prep the oven and eggplant: Heat oven to 425°F (220°C). Line two baking sheets with parchment. Arrange eggplant slices in a single layer, brush with olive oil, and season with salt and pepper. Roast 20–25 minutes, flipping halfway, until tender and lightly browned. Set aside. Lower oven to 375°F (190°C).

Cook the chicken: While eggplant roasts, heat 1 tablespoon olive oil in a large skillet over medium-high. Season chicken with salt, pepper, and 1 teaspoon Italian seasoning. Sear in batches 5–7 minutes total, until just cooked through with some color. Transfer to a plate.

Build the sauce: In the same skillet, add another drizzle of oil if needed. Sauté onion 3–4 minutes until soft. Add garlic and cook 30 seconds. Stir in crushed tomatoes, tomato paste, chicken broth, remaining Italian seasoning, and red pepper flakes. Simmer 8–10 minutes until slightly thickened. Taste and adjust salt and pepper.

Combine chicken and sauce: Return chicken and its juices to the skillet. Stir to coat and let it simmer 2–3 minutes so flavors marry. Turn off heat and fold in half the chopped basil or parsley.

Assemble the bake: Lightly oil a 9x13-inch baking dish. Add a thin layer of sauce-chicken mixture to coat the bottom. Add a layer of roasted eggplant slices. Top with more sauce, then sprinkle with half the mozzarella and half the Parmesan.

Repeat layers: Add a second layer of eggplant, then the remaining sauce and cheeses. You want the top fully covered with cheese for even browning.

Bake: Cover loosely with foil and bake at 375°F (190°C) for 15 minutes. Remove foil and bake 10–15 minutes more, until bubbly and golden in spots.

Rest and finish: Let the bake rest 10 minutes so it sets and slices cleanly. Top with the remaining fresh basil or parsley before serving.