Heat 1 tablespoon butter in a small skillet over medium heat. Cook mushrooms in butter until soft.
In a large bowl, mix the mushrooms, soup, celery, sour cream, bell pepper, and wine. Transfer to a 9x13 inch baking dish. Top with the chicken breasts. Season with paprika, garlic powder, and pepper. Top each breast with 1/2 teaspoon butter.
Cover, and bake 1 hour in the preheated oven, or until the chicken is no longer pink and the juices run clear.