For the meat filling: Preheat oven to 400 degrees F. Heat oil in a large ovenproof skillet over moderate heat. Cook onions until soft. Add lamb and garlic, and cook until browned, stirring occasionally. When meat is well browned, stir in remaining ingredients. Transfer to oven and bake until quite dry, about 45 minutes. Set aside to cool.
For the eggplant: Cut eggplant into 1/4 inch slices, lengthwise. Sprinkle with salt on both sides, and let rest on a rack until moisture rises to surface, about 30 minutes. Pat dry with paper towels. Heat oil in a large skillet over medium-high heat. Fry eggplant briefly, 1 to 2 minutes per side. Set aside to drain on paper towels.
For the vegetable filling: Wash and dry all vegetables, then cut into fine julienne. Blanch carrots and peas in a small saucepan of boiling water just until water returns to a boil. Refresh in cold water, drain, and reserve.
Melt butter in a medium skillet over moderate heat. Cook leeks along with salt 1 minute, add celery and cook 1 minute, then mushrooms and cook and additional minute. Set aside to cool. Toss all vegetables together in a large bowl and reserve.
For the custard: Combine eggs, cream, salt, pepper, and nutmeg in a bowl. Whisk until smooth. Pass through a strainer to remove any stray eggshells. Whisk in Parmesan cheese and set aside.
To assemble: Preheat oven to 350 degrees F. Stir one third of custard into meat filling. Combine remaining custard with vegetable filling.
In a 9 by 13 inch roasting pan or casserole, arrange one third eggplant slices to completely cover bottom. (The slices may overlap. That's fine.) Spread half meat filling on top, then cover with another third eggplant slices. Pour all vegetables in custard on top. Cover with remaining eggplant, then spread remaining meat mixture evenly over top.
Place the moussaka pan inside a larger roasting pan and pour boiling water into roasting pan until it rises halfway up the sides of the moussaka pan. Bake, uncovered, until custard is set in center, about 1 1/2 hours. You can test for doneness by sticking a knife in the center. If custard oozes out, cook longer.
Cut into individual portions and lift out with a spatula. Serve immediately, topped with Pimento Sauce. Moussaka can be made 1 or 2 days in advance and reheated in a 325 degree oven for 25 minutes.
Copyright 1997, M.S. Milliken & S. Feniger, all rights reserved