Heat olive oil in a large sauté pan over medium-high heat. Add the ground meat and cook until browned, stirring occasionally. Add the onion and garlic halfway through cooking, seasoning with salt. Stir in allspice, cinnamon, black pepper, oregano, and tomato paste. Cook for 2–3 minutes, then deglaze the pan with red wine. Simmer uncovered for 20 minutes, then stir in lemon zest and juice. Adjust salt to taste and set aside.

Combine 1/2 cup salt with 8 cups of water in a large pot to create a brine. Slice the eggplants into 1/4-inch rounds, peel them partially for a striped effect, and soak in the brine for 15–20 minutes. Pat the slices dry and either grill or broil them until lightly browned. Set aside.

Peel and slice the potatoes into 1/4-inch rounds. Boil them in salted water for 5–8 minutes until tender but not fully cooked. Drain and set aside.

Heat the milk in a saucepan until steamy but not boiling. In a separate pan, melt butter over medium heat, then whisk in the flour to form a roux. Gradually add the warm milk while whisking constantly. Stir until thickened, then temper the egg yolks by mixing them with a ladle of hot béchamel. Add the tempered egg mixture back into the béchamel, season with nutmeg and salt, and keep warm.

Preheat the oven to 350°F. Layer the potato slices in a casserole dish. Add half the eggplant slices, followed by the meat sauce, and then the remaining eggplant slices. Sprinkle half the grated cheese on top. Pour the béchamel sauce evenly over the layers and finish with the remaining cheese.

Bake the moussaka for 30–45 minutes, or until the top is golden brown. Let it cool for at least 15 minutes before serving.