Stir the cornstarch and 1/4 cup broth in a small bowl until the mixture is smooth.
Heat the remaining broth, garlic powder, broccoli, carrots, pepper and onion in a 3-quart saucepan over medium heat to a boil. Reduce the heat to low. Cover and cook for 5 minutes or until the vegetables are tender-crisp.
Stir in the cornstarch mixture. Cook and stir until the mixture boils and thickens. Stir in the turkey and cook until the mixture is hot and bubbling. Add the spaghetti and cheese and toss to coat.
Time-Saving: You can use 3 cans (4.5 ounces each) Swanson® Premium White Chunk Chicken Breast in Water, drained, for the turkey in this recipe.