Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Slice the eggplant and zucchini into thin rounds, brush lightly with olive oil, and season with a pinch of sea salt and black pepper.
Roast the vegetable slices for 15 minutes until they are tender and slightly golden, then remove from the oven.
While the vegetables roast, heat a skillet over medium heat and brown the ground lamb with the diced onion and minced garlic until the meat is fully cooked.
Drain any excess fat from the skillet, then stir in the tomato puree, cinnamon, and oregano, simmering for 5 minutes until the sauce has thickened.
In a small mixing bowl, whisk together the Greek yogurt and egg white until the mixture is smooth and aerated.
In a small oven-safe baking dish, layer half of the roasted eggplant and zucchini, followed by the lamb mixture, and then the remaining vegetable slices.
Pour the yogurt mixture evenly over the top layer and sprinkle with the grated parmesan cheese.
Bake for 20 to 25 minutes until the topping is set and has developed a beautiful golden-brown color.