3. mix butter until creamy. add the sugar and beat until fluffy. mix in egg and 1/2 t vanilla. mix in the flour mixture in 3 batches, alternating with the buttermilk.
4. spoon batter onto cookie sheet and bake from 10-12 minutes or until the bottoms start to turn brown. let cool on cookie rack.
5. whisk confectioners sugar, corn syrup, remaining vanilla and 1 T water together until smooth. transfer half to small bowl and mix in the cocoa. spread vanilla icing on one half of each cookie and the chocolate on the other half of each cookie.