Melt 1 Tbsp. margarine in large nonstick skillet over medium-high heat and cook chicken, turning once, 8 minutes or until thoroughly cooked. Remove chicken and set aside.
Melt remaining 1 Tbsp. margarine and cook onion, stirring occasionally, 3 minutes or until tender. Add water and milk and bring to a boil. Stir in Knorr® Italian Sides™ - Alfredo and continue boiling until pasta is tender, about 7 minutes. Return chicken to skillet, then evenly top with green beans and vegan mozzarella-style shreds. Cover and remove from heat. Let stand until cheese is melted, about 1 minute.
Sprinkle with blue cheese and freshly grated black pepper.