In cup mix cornstarch and 1/4 cup broth until smooth. Set aside. In medium saucepan mix remaining broth, garlic powder, squash, beans, carrots, pepper and onion. Over medium-high heat, heat to a boil. Reduce heat to low. Cover and cook 5 minutes or until vegetables are tender-crisp. Stir cornstarch mixture and add. Cook until mixture boils and thickens, stirring constantly. Add chicken and heat through. Toss with spaghetti and cheese.