Preheat your oven to 400°F and line a baking sheet with parchment paper.
Slice the eggplant into half-inch rounds, brush lightly with olive oil, and roast for 15 minutes until softened and slightly browned.
While the eggplant roasts, brown the ground lamb in a skillet over medium heat with the diced onion and minced garlic until the meat is fully cooked.
Stir in the tomato puree, cinnamon, oregano, sea salt, and black pepper, then simmer the sauce for 5 minutes to allow the flavors to meld.
In a small mixing bowl, whisk together the Greek yogurt, egg, and parmesan cheese until the mixture is smooth and well combined.
In a small oven-safe baking dish, layer half of the roasted eggplant, top with the lamb mixture, and then add the remaining eggplant slices.
Pour the yogurt mixture evenly over the top layer and bake for 20 to 25 minutes until the topping is set and beautifully golden.