Preheat oven to 400°F. Line baking sheets with parchment.
Brush eggplant slices with olive oil and sprinkle lightly with salt. Roast 15–20 minutes until tender. Set aside.
In a skillet, cook ground beef with onion until browned. Drain excess fat. Add garlic, marinara, Italian seasoning, salt, and pepper. Simmer 10 minutes.
In a bowl, mix ricotta, egg, and Parmesan until smooth.
In a greased baking dish, layer eggplant slices, followed by meat sauce, ricotta mixture, and mozzarella. Repeat layers until ingredients are used up, finishing with mozzarella on top.
Bake uncovered for 25–30 minutes until cheese is melted and bubbly.
Let rest 10 minutes before slicing. Garnish with fresh basil.