Preheat oven to 375°F Grease cookie sheets; set aside.
Beat butter and sugar in large bowl until light and fluffy. Beat in egg white, vanilla and salt. Gradually add flour. Beat until well blended. Drop rounded teaspoonfuls of batter 4 inches apart onto prepared cookie sheets. (Bake only 4 cookies per sheet.) Flatten slightly with spatula.
Bake 6 to 8 minutes or until cookies are deep golden brown. Let cookies stand on cookie sheet 1 minute. Working quickly, while cookies are still hot, drape cookies over rolling pin or bottle so both sides hang down and form saddle shape; cool completely.
Melt chocolate in small heavy saucepan over low heat, stirring constantly.
Tilt saucepan to pool chocolate at one end; dip edge of each cookie, turning slowly so entire edge is tinged with chocolate.
Transfer cookies to waxed paper; let stand at room temperature 1 hour or until set. Store tightly covered at room temperature. Do not freeze.