Melt 1 tablespoon shortening and unsweetened chocolate in a small saucepan, stirring until smooth. Set aside. Cream butter and shortening; gradually add sugar to creamed mixture, beating well at medium speed of an electric mixer. Add eggs, one at a time, beating after each addition. Dissolve soda in buttermilk. Combine flour and salt; add to creamed mixture alternately with buttermilk, beginning and ending with flour mixture. Mix just until blended after each addition. Stir in flavorings. Remove 2 cups of batter, and add chocolate mixture, stirring until blended. Spoon one-third of remaining plain batter into a greased and floured 25 cm tube pan; top with half of chocolate batter. Repeat layers, ending with plain batter. Gently swirl batter with a knife to create a marble effect. Bake at 180ºC or 1 hour or until a wooden pick inserted in center comes out clean. Cool in pan 10 to 15 minutes; remove from pan, and let cool completely on a wire rack. ----