PASTA AND LAMB CASSEROLE (PASTITSIO)

Steps:

• Make meat sauce:
• Cook onions in oil in a 12-inch heavy skillet over medium heat, stirring frequently, until softened, about 7 minutes. Add garlic and cook, stirring, 1 minute. Increase heat to high, then stir in lamb and cook, stirring occasionally and breaking up any lumps with a fork, until meat starts to brown, about 15 minutes.
• Meanwhile, drain both cans of tomatoes, reserving juice, and chop.
• Pour off excess fat from skillet, then stir in tomatoes with their juice, thyme, spices, and 1 1/2 teaspoons salt. Simmer over low heat, partially covered, until some liquid has evaporated but sauce is still moist, about 40 minutes. Discard thyme.
• Make béchamel while meat sauce simmers:
• Melt butter in a heavy medium pot over medium heat. Whisk in flour, then cook roux, whisking frequently, until pale golden, about 6 minutes.
• Meanwhile, heat milk in a heavy medium saucepan until just about to boil. Add milk to roux in a stream, whisking constantly until very smooth. Bring sauce to a boil over medium heat, whisking, then cook, whisking, 1 minute. Remove from heat and stir in nutmeg, cheese, and 1 tablespoon salt.
• Lightly beat yolks in a bowl. Gradually whisk in 2 cups béchamel, then whisk yolk mixture into remaining béchamel in saucepan. Cover with a round of buttered wax paper (buttered side down).
• Cook pasta and assemble pastitsio:
• Preheat oven to 375°F with rack in middle. Cook ziti in a pasta pot of boiling salted water (3 tablespoons salt for 6 quarts water) until al dente.
• Drain pasta, then transfer to a large bowl and stir in 1 cup béchamel.
• Arrange one third of pasta lengthwise in 1 layer in a large (17-by 11-inch) baking pan (about 2 inches deep).
• Add half of meat sauce (about 3 cups) to baking pan, spreading evenly over pasta.
• Make another layer of pasta and top with remaining meat sauce, then arrange remaining pasta on top.
• Spread remaining béchamel (about 6 cups) evenly over top layer of pasta.
• Stir together bread crumbs and cheese and sprinkle evenly over top of pastitsio.
• Bake until crumbs are golden brown and sauce is bubbling, about 45 minutes.