Cook pasta as directed, drain. Run under cold water and drain again. Heat 3 tbsp salad dressing in lg skillet over med-high heat. Add chicken and saute for 5 mins, or until browned. Add green onions, peas and carrots. Cook 5 min, stirring occasionally.
Add spinach to skillet. Cook until spinach is wilted. Toss all ingredients w/ pasta and serve w/ remaining dressing on the side.