Florentine Stuffed Shells
["3 Tbsp. cornstarch", "1 1/2 tsp. salt, divided", "3 c. milk", "1/4 c. margarine", "1 1/2 c. (6 oz.) Swiss cheese, shredded", "4 oz. sweet Italian sausage, crumbled", "1/4 c. chopped onion", "2 c. coarsely chopped cooked chicken", "1 pkg. frozen, chopped spinach, thawed and well drained", "1/3 c. Parmesan cheese", "1/8 tsp. pepper", "6 oz. (about 16) Mueller's jumbo shells, cooked and drained"]
["In a 2-quart saucepan, stir together cornstarch and 1 teaspoon salt.", "Gradually stir in milk until smooth.", "Add margarine, stirring constantly.", "Bring to boil over medium heat and boil 1 minute.", "Remove 1 cup sauce and set aside.", "Stir Swiss cheese into remaining sauce until melted."]
["cornstarch", "salt", "milk", "margarine", "Swiss cheese", "sweet Italian sausage", "onion", "chicken", "frozen", "Parmesan cheese", "pepper", "jumbo shells"]