Cook pasta in large saucepan as directed on package, adding vegetables during the last 3 to 4 minutes of cooking. Drain well. Place in serving bowl.
Meanwhile, stir milk gradually into Sauce Mix with whisk in small saucepan until well blended. Add butter. Stirring frequently, cook on medium heat until sauce comes to boil. Reduce heat to low; simmer 2 minutes, stirring occasionally. (Sauce will thicken upon standing.) Serve over pasta and vegetables. Sprinkle with grated Parmesan cheese, if desired.