Cream butter and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Add melted candy bars and buttermilk, and mix well.
Combine flour, salt, and soda; add to chocolate mixture, mixing well. Add pecans, chocolate syrup, and vanilla, blending well.
Spoon batter into a greased and floured 10 inch tube or Bundt pan. Bake at 325 degrees for 1 hour and 15 minutes or until done. When cake is cool, sift powdered sugar over cake, if desired.