Pasta and Lamb Casserole (_Pastitsio_) Recipe

Ingredients

• 2 medium onions, finely chopped
• 2 tablespoons olive oil
• 2 large garlic cloves, finely chopped
• 2 pounds ground lamb
• 1 (28-ounces) can whole tomatoes in juice
• 1 (15-ounces) can whole tomatoes in juice
• 4 thyme sprigs
• 1 1/4 teaspoons ground cinnamon
• 1 1/4 teaspoons ground allspice
• 1/2 teaspoon grated nutmeg
• 1/4 teaspoon ground cloves
• 7 tablespoons unsalted butter
• 6 tablespoons all-purpose flour
• 7 cups whole milk
• 3/4 teaspoon grated nutmeg
• 1 cup grated Parmigiano-Reggiano or kefalotyri cheese (2 ounces)
• 5 large egg yolks
• 2 pounds ziti
• 1 3/4 cups coarse fresh bread crumbs (from 4 slices firm white sandwich bread)
• 1/4 cup grated Parmigiano-Reggiano or kefalotyri cheese