Slice the eggplants, zucchini, and potatoes into ¼-inch rounds. Sprinkle salt over eggplant slices and let sit in a colander for 30 minutes to draw moisture out. Rinse and pat dry.

Heat olive oil in a large skillet. Fry salted eggplant, zucchini, and potato rounds in batches until golden and tender, about 4-5 minutes per side. Drain on paper towels.

In the same skillet, sauté chopped onions until translucent (about 5 minutes). Add minced garlic and cook for another minute. Add ground meat, crumbling it as it cooks until browned (6-8 minutes). Pour in red wine, simmer for 2-3 minutes, then stir in crushed tomatoes and spices. Simmer for 10-15 minutes until thickened.

Melt butter in a saucepan over medium heat, whisk in flour, cooking for about 2 minutes. Gradually add milk, whisking continuously until thickened (5-7 minutes). Remove from heat and stir in egg yolks, nutmeg, and cheese until smooth.

Layer potatoes, eggplant, zucchini, and half the meat sauce in a baking dish. Repeat layering, finishing with meat sauce, and pour béchamel over the top.

Preheat oven to 350°F (175°C). Bake moussaka for 40-45 minutes until top is golden brown and bubbly. Allow to cool for at least 30 minutes before serving.