The only changes I make in this recipe is to add more cheese to the custard topping, and more oregano to the meat sauce. A tip for consistently good results with this recipe is to slice the eggplant as thin as possible.
I have tried this recipe with ground beef (my favorite) and ground turkey (very good). I haven't yet tried it with ground soy, but that will be my next attempt. If I'm successful, I'll make vegetarian shortcut moussaka for my meat-shunning neighbors.
This dish is perfect for cooking on Sunday, portioning into containers, and taking for lunch during the week.