Lamb Pasticcio

Preheat the broiler. Put the egg yolks in a bowl and set aside. Season the lamb generously with salt and pepper.

Heat the olive oil in a large, heavy-bottomed pot over medium-high heat until hot but not smoking. Add the onion and cook until softened, about 4 minutes. Add the lamb and cook, breaking it up with a wooden spoon, until browned, about 10 minutes. Transfer the lamb-onion mixture to a bowl and stir in the chopped tomatoes, tomato paste, parsley and oregano. Set aside.

Wipe out the pot, add the butter and cook over medium heat until the butter is completely melted. Add the flour a little at a time, whisking it into the butter to incorporate thoroughly without making lumps. Slowly drizzle in the milk, letting it come briefly into contact with the bottom of the hot pot to warm it a bit before whisking it into the mixture. Add a few tablespoons of the hot mixture to the bowl with the egg yolk and whisk it in, then pour the entire mixture into the pot. Whisk in the Parmesan.

Place a casserole in the oven to warm it. Spoon about 1 cup of the bechamel sauce into a bowl and set aside. Stir the reserved lamb and the pasta into the remaining bechamel in the hot pot. Remove the casserole from the oven and transfer the contents of the pot into it. Top with the reserved bechamel, using a spatula or the back of a spoon to spread it evenly over the top of the casserole.

If not serving immediately, let cool, cover and refrigerate for a few days or freeze up to 1 month. Reheat before proceeding.

Return the casserole to the oven and broil until lightly browned on top, about 2 minutes. Serve the pasticcio family-style from the center of the table.