Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
Slice the eggplant into 1/2-inch thick rounds, sprinkle with a pinch of sea salt, and roast for 15-20 minutes until tender.
While the eggplant roasts, heat a skillet over medium heat and brown the ground lamb with the diced yellow onion and minced garlic until the meat is cooked through.
Stir in the tomato puree, cinnamon, oregano, and black pepper, then simmer the meat sauce for 5 minutes to allow the flavors to meld.
In a small bowl, whisk together the Greek yogurt, egg, and ground nutmeg until smooth and well combined.
In a small oven-safe dish, layer half of the roasted eggplant slices, followed by the lamb sauce, and then the remaining eggplant slices.
Pour the yogurt and egg mixture over the top, spreading it evenly to the edges.
Bake for 20-25 minutes until the topping is set and develops a beautiful golden-brown color.