Cook pasta in a large saucepan according to package directions, adding the vegetables during the last 6 minutes of cooking.
Meanwhile, in a large nonstick skillet coated with cooking spray, brown sausage; remove from skillet and keep warm.
In a small bowl, combine the flour, garlic powder, mustard and pepper flakes; gradually whisk in milk until smooth. Add milk mixture to the skillet, stirring to loosen browned bits from pan. Bring to a boil; cook and stir for 1-2 minutes or until thickened.
Drain pasta and vegetables; stir into the pan. Add cheese and reserved sausage; cook and stir until cheese is melted. Yield: 4 servings.