In a heavy skillet, melt butter over medium heat. Brown chicken on both sides. Remove chicken. Drain. Reduce heat to simmer. Stir in soup. Cook and stir until pan drippings are loosened from bottom of pan. Add sour cream or yogurt 1/2 cup at a time, stirring until well-mixed. Add chicken. Cover and simmer over very low heat until tender about 45-60 minutes. Sauce should boil. Stir in mushrooms and heat through. Serve immediately over rice or pasta.
Cajun Country -- New Iberia, Louisiana