Preheat oven to 350 degrees F. Grease and flour 10 inch tube pan or 12 cup fluted pan.
Beat butter in large bowl until creamy, gradually add granulated sugar, beating on medium speed until well blended. Add eggs, one at a time, beating well after each addition. Add chocolate, beat until blended.
Stir together flour, baking soda and salt; add to chocolate mixture alternately with buttermilk, beating until well blended. Add syrup and vanilla, beat until well blended. Stir in pecans. Pour batter into prepared pan.
Bake 1 hour and 15 minutes or until wooden pick inserted in center of cake comes out clean. Cool 10 minutes, remove from pan onto wire rack. Cool completely. Dust with sifted powdered sugar and drizle with chocolate syrup , if desired
* To sour milk use 1 tablespoon of white vinegar plus milk to equal 1 cup