Preheat oven to 350. Cream butter and sugar. Add eggs one at a time, beating well after each addition. Melt Hershey bar and add to batter along with Hershey syrup and buttermilk to batter. Sift flour, baking soda and salt and blend into mixture. Add vanilla. Bake in well greased and floured bunt pan for 50-60 minutes. Cool in pan for 1 hour. Remove and dust with sifted powdered sugar.