Using an electric mixer cream butter and shortening. Add sugar a little at a time until it's all creamed together.Add one egg at a time as you continue to mix the batter. Add the vanilla.In another bowl mix all the dry ingredients. Add milk and dry ingredients in thirds, alternately, as you continue to mix the batter.Pour into greased and floured bundt pan or 2 loaf pans. Bake 1 hour, or until toothpick inserted in the center of the cake comes out clean.