1. Prepare the Vegetables

• Preheat your oven to 400°F (200°C).
• Brush the sweet potato and eggplant slices with olive oil and sprinkle with salt and pepper.
• Arrange them in a single layer on baking sheets.
• Roast for 20–25 minutes, flipping halfway through, until tender and lightly golden. Set aside.

2. Make the Meat Sauce

• Heat 1 tbsp olive oil in a skillet over medium heat.
• Sauté the chopped onion until soft (about 5 minutes), then add garlic and cook for another minute.
• Add the ground beef or lamb and cook until browned. Drain excess fat if needed.
• Stir in cinnamon, allspice, oregano, and tomato paste. Cook for 2 minutes to bloom the spices.
• Pour in the crushed tomatoes and red wine (if using). Season with salt and pepper.
• Simmer for 15–20 minutes until thickened. Remove from heat and set aside.

3. Prepare the Béchamel Sauce

• Melt the butter in a saucepan over medium heat.
• Whisk in the flour and cook for 1–2 minutes to form a roux.
• Gradually whisk in the warm milk, stirring constantly to avoid lumps.
• Cook until the sauce thickens, then season with nutmeg, salt, and pepper.
• Remove from heat, stir in the Parmesan cheese, then let cool slightly.
• Whisk in the egg once the sauce has cooled a little (to avoid scrambling it).

4. Assemble the Moussaka

• Grease a 9×13-inch baking dish.
• Layer 1: Arrange a layer of roasted eggplant slices on the bottom.
• Layer 2: Spread half the meat sauce evenly over the eggplant.
• Layer 3: Add a layer of sweet potato slices.
• Layer 4: Spread the remaining meat sauce over the sweet potatoes.
• Layer 5: Top with remaining eggplant slices.
• Finish: Pour the béchamel sauce over the top and smooth it out.

5. Bake the Moussaka

• Reduce oven temperature to 375°F (190°C).
• Bake uncovered for 35–40 minutes, or until the béchamel is golden and bubbling.
• Rest for 15–20 minutes before slicing. This helps the layers set.

6. Serve

• Garnish with chopped parsley or fresh oregano.
• Serve warm, ideally with a crisp salad and crusty bread.