Combine flour, baking soda, salt, white sugar, butter or margarine, brown sugar, eggs and vanilla. Combine and mix at lowest speed until dough forms.
Drop by scant teaspoons 2 inches apart on greased cookie sheets. Press candy wafer on top of each - mold dough sides up around mint. Cover with scant teaspoons of dough. Top each with walnut half.
Bake at 375 degrees F (190 degrees C) for 9-12 minutes.