Use 8 chicken breasts, boned if desired. Wash and dry. Shake in flour and season with salt and pepper. Brown in butter. Arrange the breasts in a baking dish in one layer. In the pan in which the chicken was browned, make a sauce by reducing the fat to 2 tablespoons. Add 1 pound sliced mushrooms. Cook mushroom slightly then add 1/2 pint sour cream, 1/2 cup dry white wine and a pinch of rosemary. Pour over chicken. Cover and bake 1 1/4 hours at 350 degrees.