Melt butter in a lightly greased 13 X 9 inch baking dish in a 425 degree oven.
Sprinkle chicken with salt and pepper. Dip chicken in 1/2 cup buttermilk, and dredge in flour. Arrange chicken, breast side down, in baking dish.
Bake at 425 for 25 minutes. Turn chicken and bake 10 minutes more. Stir together remaining 1 cup of buttermilk and cream of mushroom soup; pour over chicken, and bake 10 more minutes, shielding chicken with aluminum foil to prevent excessive browning, if necessary. Garnish, if desired with lemon wedges.