Cream butter gradually add sugar, beating until light and fluffy. Add egg; beat well.
Combine flour, baking powder, and salt; add to creamed mixture alternately with buttermilk, beginning and ending with flour mixture. Gently stir in vanilla.
Drop batter by heaping teaspoonfuls onto ungreased cookie sheets. Bake at 350° for 12 minutes or until lightly browned. Cool on wire racks.