Lamb and Eggplant Pastitsio

Name: Lamb and Eggplant Pastitsio
Ingredients: 1 large onion, chopped; 1 tablespoon olive oil; 1 lb lean ground lamb; 1 garlic clove, minced; 1 1/2 teaspoons salt; 1 teaspoon dried oregano, crumbled; 1/2 teaspoon cinnamon; 1/4 teaspoon sugar; 1/4 teaspoon black pepper; 1 lb eggplant, peeled and cut into 1/2-inch cubes; 1 (28- to 32-oz) can crushed tomatoes; 2 tablespoons unsalted butter; 2 tablespoons all-purpose flour; 2 cups milk; 1 garlic clove; 1 whole clove; 1/2 lb feta, crumbled; 1/2 teaspoon salt; 2 large eggs; 10 oz penne (3 cups)