Pastitsio

Name: Pastitsio
Ingredients: 1/4 cup extra-virgin olive oil; 1/2 cup chopped onion; 1 tablespoon chopped fresh garlic; Freshly ground black pepper; 2 bay leaves; 2 cinnamon sticks; 3 to 4 whole cloves; 2 pounds ground beef (80/20); Salt; 1/2 cup peeled and chopped fresh tomatoes; 1 tablespoon tomato puree; 1 tablespoon margarine, melted; 1 pound ziti, cooked; 1 egg, beaten; 2 tablespoons grated Parmigiano-Reggiano, plus more for topping; Bechamel Sauce, recipe follows; 1 quart milk; 1 cup (2 sticks) margarine; 1 cup all-purpose flour; 2 eggs, beaten; 2 tablespoons grated Parmigiano-Reggiano; Salt and freshly ground black pepper; Freshly ground nutmeg