2 c  Flour

    1/2 ts Baking powder

    1/4 ts Salt

    1/2 c  Light brown sugar, packed

    1/2 c  Sugar

    1/2 c  Butter, softened

      1 lg Egg

    1/2 c  Sour cream

      1 ts Vanilla extract

      1 c  Semisweet chocolate chips

     Preheat oven to 300*F.  In medium bowl combine flour, baking
  powder and salt with wire whisk. Set aside. Combine sugars in a large
  bowl using and electric mixer set at medium speed.  Add butter and
  beat until batter is grainy.  Add egg, sour cream and vanilla, and
  beat at medium speed until light and flufffy. Scrape bowl. Add the
  flour mixture, and blend at low speed until just combined.  Place
  chocolate chips in double boiler over hot but not boiling water. Stir
  constantly until melted. Or, place chips in a microwave proof bowl
  and zap on high, stirring every 20 seconds until melted.  Cool
  chocolate for a few minutes and pour over cookie batter. Using a
  wooden spoon or rubber spatula, lightly fold melted chocolate int the
  dough.  Do not mix chocolate completely into dough. Drop by rounded
  tablespoons, 2 inches apart, onto ungreased cookie sheets. Bake 23-25
  minutes.  Do not brown. Quickly transfer cookies to a cool surface.