Preheat your oven to 400°F and line a baking sheet with parchment paper.
Slice the eggplant and zucchini into 1/2-inch thick rounds, brush lightly with half of the olive oil, and roast for 15 minutes until softened.
While vegetables roast, heat the remaining olive oil in a skillet over medium heat and sauté the diced onion and minced garlic until fragrant.
Add the ground beef to the skillet, browning it thoroughly while breaking it into small crumbles with a spatula.
Stir in the tomato puree, ground cinnamon, sea salt, and black pepper, then let the sauce simmer on low for 10 minutes.
In a small mixing bowl, whisk together the Greek yogurt and the egg until the mixture is completely smooth and combined.
In a small oven-safe baking dish, layer half of the roasted eggplant and zucchini, followed by the meat sauce, and then the remaining vegetables.
Pour the yogurt and egg mixture over the top, spreading it evenly to the edges.
Bake for 20-25 minutes until the topping is set and develops a beautiful golden-brown color.
Remove from the oven, let it rest for 5 minutes, and garnish with chopped fresh parsley before serving.