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 20 minutes until tender.
While eggplant roasts, sauté the diced onion and minced garlic in a skillet over medium heat until translucent.
Add the ground beef to the skillet, browning it thoroughly and draining any excess fat.
Stir in the tomato puree, cinnamon, sea salt, and black pepper, then simmer the meat sauce for 10 minutes.
In a small bowl, whisk together the Greek yogurt, egg, and nutmeg until smooth to create the topping.
In a small oven-safe dish, layer half of the roasted eggplant, followed by the beef mixture, and the remaining eggplant.
Spread the yogurt mixture evenly over the top layer and bake for 20-25 minutes until the topping is set and slightly browned.