1.Stir The Cornstarch And 1/4 Cup Broth In A Small Bowl Until The Mixture Is Smooth. 2.Heat The Remaining Broth, Garlic Powder, Broccoli, Carrots, Pepper And Onion In A 3-Quart Saucepan Over Medium-High Heat To A Boil. Reduce The Heat To Low. Cover And Cook For 5 Minutes Or Until The Vegetables Are Tender-Crisp. 3.Stir The Cornstarch Mixture In The Saucepan. Cook And Stir Until The Mixture Boils And Thickens. Stir In The Chicken And Cook Until The Mixture Is Hot And Bubbling. Toss The Chicken Mixture With The Spaghetti And Cheese.