Turkey Tetrazzini
["8 oz. dry spaghetti or noodles", "3 Tbsp. butter or margarine", "1 small onion, chopped", "1/4 c. all-purpose flour", "2 3/4 c. milk", "1 (2 1/2 oz.) jar sliced mushrooms", "1 chicken bouillon cube or pkg.", "1/2 tsp. salt", "1/4 tsp. pepper", "1/4 c. grated Parmesan cheese", "3 Tbsp. margarine", "4 slices white bread", "2 c. cubed, cooked turkey"]
["Baking Temperature: 350\u00b0.", "Baking Time: 20 minutes."]
["noodles", "butter", "onion", "all-purpose", "milk", "mushrooms", "chicken", "salt", "pepper", "Parmesan cheese", "margarine", "white bread", "turkey"]