Place pistachios on baking sheet; bake at 300°F. to keep warm while preparing candy.  Combine sugar, butter, water and corn syrup.  Cook, without stirring, to soft crack stage (275°F. on candy thermometer).  Add brandy flavoring and pistachios.  Pour onto foil-lined baking sheet.  Sprinkle chocolate chips over hot candy and allow to stand for three minutes.  Spread the melted chocolate over the candy with a knife.  Cool.  Break into serving-sized pieces.