Salt and dry the eggplant: Salt the rounds lightly, let sit 20–30 minutes, then pat dry. This improves texture and reduces moisture.
Bake the eggplant: Heat oven to 425°F. Dip slices lightly in egg/egg whites, coat with panko seasoned with garlic powder, Italian seasoning, pepper, and half the Parmesan. Spray both sides and bake 15–20 minutes, turning once, until browned.
Cook the protein: Brown the turkey with garlic, oregano, pepper, and red-pepper flakes; add ½ cup marinara. If using leftover cooked chicken, warm it directly in the sauce.
Assemble: In an 8×8 pan, layer a little marinara, half the eggplant, the meat mixture, more eggplant, remaining sauce, mozzarella, and remaining Parmesan.
Finish: Bake at 375°F for 15–20 minutes until bubbling and browned; rest 5–10 minutes before serving.