HEAT oil in large skillet on medium-high heat. Add chicken and onions; cook and stir 5 min. Add paprika; cook and stir 1 min.
ADD water and Shell Macaroni; stir. Bring to boil; cover. Simmer on medium-low heat 12 min. or until Shells are tender and most of the water is absorbed.
STIR in Cheese Sauce and sour cream; cook 5 min. or until heated through, stirring occasionally.