In a mixing bowl, cream butter and sugar until light and fluffy.
Beat in egg and vanilla.
Combine flour, baking soda and salt; add to the creamed mixture alternately with buttermilk and mix well
. Drop by rounded tablespoonfuls two inches. apart onto greased baking sheets.
Bake at 375 degrees F for 10-12 minutes or until edges are lightly browned.Remove to wire racks to cool