Preheat your oven to 400°F and line a baking sheet with parchment paper.
Slice the eggplant into 1/2-inch thick rounds, brush both sides with olive oil, and sprinkle with sea salt.
Roast the eggplant for 15-20 minutes until tender and slightly browned.
While eggplant roasts, finely dice the onion and mince the garlic.
In a skillet over medium heat, brown the ground lamb with the onion and garlic until the meat is fully cooked.
Stir in the tomato puree, cinnamon, oregano, and black pepper, then simmer for 5 minutes to thicken.
In a small bowl, whisk together the Greek yogurt and the egg until smooth.
In a small oven-safe baking dish, layer half of the roasted eggplant, followed by the lamb mixture, and then the remaining eggplant.
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 golden brown.