Prepare rigatoni according to package directions; drain. Melt margarine in large saucepan; blend in flour. Stir in milk and chicken broth; continue cooking, stirring constantly, until sauce is smooth and thickened. Stir in turkey, mushrooms, half and half, sherry, salt, pepper and nutmeg. Spoon half of rigatoni into bottom of buttered 3-quart casserole; top with half of sauce mixture. Repeat layers. Bake, covered, in a preheated 350 F oven 45 minutes. Sprinkle top with Parmesan cheese and almonds. Continue baking, uncovered, until bubbly (15-25 minutes). Let stand 10 minutes.