Green and White Lasagna

6 pieces lasagna, uncooked
1/2 cup chopped onion
2 tablespoons margarine
2 tablespoons cornstarch
1 tablespoon dried parsley flakes
1 teaspoon dried basil, crushed
1/4 teaspoon garlic powder
1/8 teaspoon ground nutmeg
2 cups skim milk
1 10 ounce package frozen chopped spinach, thawed and drained
1 2 1/4 ounce can sliced pitted ripe olives, drained
1 15 ounce carton part skim ricotta cheese
1 beaten egg
1 8 ounce package shredded mozzarella cheese
1/2 cup grated Parmesan cheese

Cook lasagne according to package directions; drain. Rinse in cold water; drain well. In a medium saucepan, cook onion in margarine until tender. Stir in cornstarch, parsley, basil, garlic powder and nutmeg. Add milk all at once. Cook and stir until thickened and bubbly. Stir in spinach and olives. In a medium bowl, stir together ricotta and egg. Add mozzarella and half of the Parmesan; mix well. Preheat oven to 350F. Arrange three of the lasagne pieces in the bottom of a greased 12 x 7 x 2 inch baking dish. Top with half of the spinach mixture and half the ricotta mixture. Repeat layers. Top with remaining Parmesan cheese. Bake for 40 minutes or until mixture is bubbly. Let stand 10 minutes. Serves 10 to 12.