Cream butter and sugar; add eggs one at a time, beat well. Add baking soda to buttermilk. Alternately add flour and buttermilk to creamed mixture. Add melted candy bar, cooled. Add syrup and vanilla. Bake at 325 for 1 hour and 10 minutes.
Icing: Cream together 2 cups sifted 6x sugar, 2 Tsp cocoa, 1 stick margarine and spread on cooled cake.