Preheat your oven to 400°F (200°C).
Slice the eggplant into rounds, brush with olive oil, and roast on a baking sheet for 10 minutes until softened.
While the eggplant roasts, place a skillet over medium heat and brown the ground lamb with the diced onion and minced garlic.
Season the lamb mixture with sea salt, black pepper, dried oregano, and cinnamon.
Stir the tomato puree into the lamb and simmer for 5 minutes until the sauce has thickened.
In a small bowl, whisk together the Greek yogurt and the egg until smooth and well combined.
In a small oven-safe dish, layer the roasted eggplant slices and the lamb mixture.
Pour the yogurt and egg mixture over the top, spreading it evenly to the edges.
Bake for 15-20 minutes until the topping is set and lightly golden brown.