This cake is basically a wintery version of my Chocolate Pumpkin Cake. I have been wanting to do another version of that cake for a year now, and this seemed like the perfect way to do it.
In a small bowl, sift the cake flour and set aside. In a large bowl, on the medium speed of an electric mixer, cream the butter and sugar until very light and fluffy, about 5 minutes.
In a measuring cup, stir the salt into the buttermilk. Add to the batter in three parts, alternating with the flour. With each addition, beat until the ingredients are incorporated, but do not overheat.
In a small bowl, stir together the cider vinegar and baking soda. Add to the batter and mix well. Using a rubber spatula, scrape down the batter in the bowl, making sure the ingredients are well blended and the batter is smooth.
Bake for 30-40 minutes, or until a cake tester inserted in the center of the cake comes out clean. Let the layers cool in the pans for 1 hour. Remove from the pans and cool completely on a wire rack.