A tube cake with half the batter colored with chocolate and folded in for a marbled effect.
Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 10 inch tube pan. Sift together the flour, baking soda and salt. Set aside.
In a large bowl, cream together the shortening and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla. Beat in the flour mixture alternately with the buttermilk, mixing just until incorporated. Pour half of the batter into prepared pan. Blend chocolate sauce with remaining batter. Pour chocolate mixture over top of other batter and fold in gently with spatula for a marble effect.
Bake in the preheated oven for 60 to 70 minutes, or until a toothpick inserted into the center of the cake comes out clean. Let cool in pan for 10 minutes, then turn out onto a wire rack and cool completely.