Preheat the oven to 325º. Grease a 9x5 loaf pan.
Combine dry ingredients. Blend egg and buttermilk together and add, all at once to the dry ingredients. Mix until just moistened. Stir in butter. Pour into the pan.
Bake for 65 to 70 minutes, or until a toothpick inserted in the bread comes out clean. Cool on a wire rack. Wrap in foil for several hours, or overnight for best flavor.