Slice the 3 large eggplants sliced into 1/2-inch rounds into 1/2-inch rounds. Lay them in a single layer on a baking sheet or in a colander, sprinkle generously with 2 tsp kosher salt for drawing out moisture on both sides, and let them sit for 20–30 minutes. This draws out moisture and bitterness. Pat very dry with paper towels.

Preheat your oven to 425°F. Arrange the dried 3 large eggplants sliced into 1/2-inch rounds slices in a single layer across two lightly oiled baking sheets. Brush both sides of each slice with 3 tbsp olive oil for brushing. Roast for 20–25 minutes, flipping once halfway through, until golden and tender. Set aside. Reduce oven temperature to 375°F.

Heat 2 tablespoons of olive oil for brushing in a large skillet over medium-high heat. Add the diced large yellow onion finely diced and cook, stirring occasionally, for 5–6 minutes until softened and lightly golden. Add the 4 cloves garlic minced and cook for 1 more minute until fragrant.

Add the 1 ½ lb ground lamb or substitute ground beef to the skillet. Break it up with a wooden spoon and cook over high heat for 6–8 minutes until browned and cooked through. Drain off any excess fat if needed.

Add the 2 tbsp tomato paste and stir to coat the meat. Cook for 1–2 minutes until it darkens slightly. Pour in the ½ cup dry red wine such as Cabernet or Merlot (if using) and let it bubble and reduce for 2 minutes. Add the 1 can crushed tomatoes, 1 tsp ground cinnamon, ½ tsp ground allspice, ¼ tsp ground nutmeg, ½ tsp dried oregano, 2 tsp kosher salt for drawing out moisture, and ½ tsp black pepper freshly ground. Stir well to combine.

Reduce the heat to medium-low and simmer the sauce uncovered for 20–25 minutes, stirring occasionally, until it is thick and most of the liquid has evaporated. The sauce should not be watery — this is key to a firm moussaka. Taste and adjust seasoning. Set aside.

Melt the 4 tbsp unsalted butter in a medium saucepan over medium heat. Add the 4 tbsp all-purpose flour all at once and whisk constantly for 1–2 minutes to cook out the raw flour taste — it should smell nutty and look pale golden.

Slowly pour in the 2 ½ cups whole milk, a little at a time, whisking constantly after each addition to prevent lumps. Once all the whole milk is incorporated, continue to cook, whisking frequently, for 4–5 minutes until the sauce is thick enough to coat the back of a spoon.

Remove the pan from the heat. Stir in the ¼ tsp ground nutmeg, 2 tsp kosher salt for drawing out moisture, and ¼ tsp white pepper. Let the sauce cool for 3–4 minutes — it should no longer be steaming. Beat the 2 eggs in a small mixing bowl, then whisk them briskly into the béchamel. Stir in half of the Parmesan cheese freshly grated. The sauce should be smooth, thick, and glossy.

Lightly grease a baking dish (9x13-inch). Arrange half of the roasted 3 large eggplants sliced into 1/2-inch rounds slices in an even layer across the bottom, overlapping slightly if needed. Spread all of the meat sauce evenly over the 3 large eggplants sliced into 1/2-inch rounds layer.

Layer the remaining large eggplants sliced into 1/2-inch rounds slices over the meat sauce. Pour the béchamel evenly over the top, spreading it to the edges with a spatula. Sprinkle the remaining Parmesan cheese freshly grated over the surface.

Bake at 375°F for 40–45 minutes, until the top is deep golden brown and the béchamel is set (it should not jiggle when you shake the dish). If the top is browning too fast, loosely tent with aluminum foil.

Remove from the oven and let the moussaka rest for at least 20–30 minutes before cutting. This resting time is essential — it allows the layers to firm up so you get clean, beautiful slices. Serve warm.