Wash chicken and pat dry. Brush with1 Tbs butter. Sprinkle with salt and pepper. Place in Crock Pot. Sprinkle with dry salad mix. Cover and cook on low for 5 to 6 hours. About 3/4 hour before serving, place remaining butter in a small saucepan and saute the onion at medium heat until it is translucent. Mix in soup, cream cheese, chicken stock (or wine). Cook until smooth. Pour over chicken in pot. Cover and cook for 30 minutes on low. Serve with sauce with rice or noodles.