It's getting on toward dinnertime, now... and I don't know Giada's recipe. But I've used this one successfully by doing everything ahead except for the final baking - both by refrigeration and freezing beforehand.
2 cups chopped celery
1 1/2 cups chopped onions
3 tablespoons butter or margarine
2 cups chicken broth
1 tablespoon Worcestershire sauce
salt and pepper to taste
1 (10-ounce) can condensed cream of mushroom soup
1/2 cup milk
1 cup grated sharp Cheddar cheese
1/2 pound spaghetti, cooked and drained
6 cups chopped, cooked chicken
1/2 cup sliced stuffed olives
1 cup chopped pecans
In saucepan, cook celery and onions in butter until tender. Add chicken broth, Worcestershire sauce, salt and pepper. Simmer about 15 minutes. Slowly stir in mushroom soup, milk and cheese; mix thoroughly. Remove from heat. Add cooked spaghetti.
Preheat oven to 350 degrees. Grease a 9 x 13-inch baking dish. Add chicken and olives to spaghetti. Place in prepared dish. Sprinkle with chopped pecans. Bake for 20 to 25 minutes or until hot and bubbly.
Makes 12 servings.
Tetrazzini may be made the day before and refrigerated or frozen and used later.