Preheat your oven to 400°F and line a baking sheet with parchment paper for easy cleanup.
Slice the eggplant into 1/2-inch thick rounds, brush both sides lightly with olive oil, and roast for 15 minutes until tender and slightly browned.
While the eggplant is roasting, heat a non-stick skillet over medium heat and sauté the diced yellow onion, minced garlic, and ground lamb until the meat is fully browned.
Stir in the tomato puree, ground cinnamon, dried oregano, sea salt, and black pepper, then let the mixture simmer for 5 minutes to meld the flavors.
In a small mixing bowl, whisk together the non-fat Greek yogurt and egg whites until the mixture is completely smooth and uniform.
In a small oven-safe baking dish, create a base layer using half of the roasted eggplant slices.
Spread the seasoned lamb mixture over the eggplant, then top with the remaining eggplant slices.
Pour the yogurt and egg white custard over the top, spreading it evenly to reach the edges of the dish.
Bake for 20 to 25 minutes until the creamy topping is set and develops a beautiful golden-brown color.