Sift first 6 ingredients together. In separate bowl, combine eggs, oil, buttermilk and vanilla. Add wet ingredients to dry, and mix well. Stir in remaining cake ingredients. Pour into greased and floured 9x13-inch baking pan. Bake at 350 F for 45 minutes, or until cake tests done.
Buttermilk Glaze: Combine in a saucepan, simmer for 5 minutes. Then stir in vanilla. Punch holes in warm cake and pour hot glaze over top.