Mix Cornstarch, Broth, Lemon Juice And Mustard. Cook Chicken And Garlic In Nonstick Skillet Until Browned, Stirring Often. Remove Chicken. Add Cornstarch Mixture. Cook And Stir Until Mixture Boils And Thickens. Return Chicken To Skillet And Heat Through. Stir In Parsley. Toss With Spaghetti.