Combine dry ingredients in a bowl set aside. Cream margarine,brown sugar until light & fluffy. Beat in chocolate,egg,vanilla & milk. Gradually add dry ingredients mixing well to make a stiff dough.Chill overnight.Roll into 1 tsp balls ,place 2" apart on an ungreased sheet.Bake 350 8min until tops are cracked.Remove from sheet & immediatlely roll in powdered sugar. Noteuse only stick margarine. The spread kind does not allow dough to become firm enough for rolling into balls