Melt butter over medium heat in a large skillet. Add 2 Tbsp. olive oil and celery. Saute until celery is tender-crisp (about 5 minutes). Add onion. Continue sauteeing until onion is transparent. Transfer vegetables into bowl and set aside. Add 2 Tbsp. olive oil to skillet, then saute diced chicken breast until done (about 10 minutes). Add vegetables back to skillet with chicken breast. Add alfredo sauce. Warm on low heat until hot, but not boiling. Serve over rice, pasta or polenta.