1 1/2 pound potatoes, pared and sliced 1 pound zucchini, sliced lengthwise 3/8 inch thick 1 tablespoon olive oil 2 medium onions, chopped 1/2 pound ground beef or lamb 1/2 pound ground turkey 3 tablespoons tomato paste 1 teaspoon oregano, crumbled 1/4 teaspoon black pepper 1/4 teaspoon cinnamon 1 teaspoon salt 2 cups low fat milk 1/4 cup flour 1 egg 1 egg white 3 tablespoons Parmesan cheese
Boil potatoes in large pot of salted water 8 to 10 minutes, until tender.
Remove with slotted spoon to colander to drain. Spread potato slices evenly in 11 x 7 x 2 inch baking dish.
Simmer zucchini in the water above for 8 to 10 minutes, until tender. Drain in colander; rinse under cold water; drain. Heat oil in nonstick skillet over medium heat. Add onion; cook 6 to 8 minutes or until softened. Add beef and turkey; cook 6 minutes or until no longer pink, breaking up meat with spoon. Pour off any fat, if necessary.
Stir in tomato paste, oregano, pepper, cinnamon and 3/4 teaspoon salt. Spoon over potato, spreading level. Arrange zucchini in single layer over meat.
Shake together 1/4 cup milk and flour in a jar. Combine with remaining 1 3/4 cup milk and remaining salt in small saucepan. Bring to simmering over medium-low heat, whisking. Beat together egg and egg white in small bowl.
Whisk some milk mixture into egg; whisk egg mixture into pan; cook 1 minute whisking constantly; do not let boil.
Spoon over zucchini, spreading level. Sprinkle with Parmesan. (Can be prepared a day ahead. Cool, refrigerate covered.) Bake in preheated 375 F oven for 30 to 35 minutes or until heated through and golden. Cut into squares and serve hot or warm.