Generously grease and flour bottoms of 3 8-inch layer cake pans. Measure sifted flour, baking soda, salt, and spices into sifter. Measure milk into a 2-cup measure; add vinegar.
In a mixing bowl, cream shortening and sugar until light and fluffy. Beat in eggs, one at a time, beating well after each addition. Sift in dry ingredients in about 4 additions, alternating with the soured milk. Beat on low speed just until blended. Stir in the apple butter and pour into pans. Bake in preheated 350Â° oven for 30 minutes, or until center springs back when lightly touched with finger. Cool in pans on racks for 5 minutes. Loosen sides with a knife; turn out onto racks. Cool layers completely. Put layers together with cream cheese frosting or a Butter Frosting, then frost sides and top. Garnish with walnuts or pecans, if desired.