Cut corn from cob; set kernals aside. Scrape juices from cob into lg. pot. Add cobs, along with chicken and 8 cups water and 1/2 tsp. salt. Heat to boiling on high then reduce to gentleman simmer for 20 to 25 minutes, until chicken is cooked. Remove from heat, let cool. Transfer chicken to lg. bowl. When cool enough to handle, remove and discard any bones. Pull meat into bitesize pieces. Remove and discard cobs from poaching liquid. Save liquid.

Heat butter and oil on high in lg. pot until butter melts. Add celery, carrots, onions and 1/2 tsp. salt. Cook 10 min. until veggies start to soften. Sprinkle flour over veggies, stir and cook for 1 min. Then stir in poaching liquid and corn kernals. Heat to boiling on high then reduce simmer for 15 min., stirring occasionally. Stir in half and half, tarragon and chicken. Remove from heat and serve.