1. Coat an 8-inch square baking dish with cooking spray; set aside. Cook spaghetti according to package directions, omitting salt and fat. Drain and set aside.
2. Preheat oven to 400°.
3. Combine broth and next 3 ingredients in a large saucepan. Bring to a boil; cover, reduce heat, and simmer 5 minutes or until vegetables are tender. Combine 1 cup evaporated milk and next 3 ingredients in a small bowl, stirring well with a whisk. Add to vegetable mixture. Cook over medium heat until mixture is thickened and bubbly, stirring constantly. Add chicken and sherry.
4. Toss cooked spaghetti with chicken mixture. Spoon into prepared baking dish. Sprinkle with Parmesan cheese. Bake, uncovered, at 400° for 10 minutes or until golden.