Preheat your oven to 400°F (200°C).
Slice the eggplant into 1/2-inch thick rounds, brush lightly with olive oil, and roast on a baking sheet for 15 minutes until tender.
While eggplant roasts, heat a skillet over medium heat and brown the ground lamb with diced onion and minced garlic until the meat is fully cooked.
Stir in the tomato puree, sea salt, black pepper, dried oregano, and ground cinnamon; simmer for 5 minutes to meld the flavors.
In a small mixing bowl, whisk together the Greek yogurt and the egg until smooth.
In a small baking dish, layer half of the roasted eggplant, top with the lamb mixture, and then the remaining eggplant slices.
Pour the yogurt and egg mixture over the top, spreading it evenly to the edges.
Bake for 20 minutes until the topping is set and develops a light golden-brown color.