Never Fail Fudge

2 ½ c. sugar

¼ c. margarine

1 small can (5oz) evaporated milk

1 jar (7.5 oz) marshmallow fluff

¾ t. salt

¾ t. vanilla

12 0z. package semi-sweet chocolate chips

Combine the first 5 ingredients. Stir over low heat until blended. Bring to a boil over moderate heat, being careful not to mistake air bubbles for boiling. Then boil slowly, stirring constantly, for 5 minutes (soft ball stage). Remove from heat. Stir in chocolate and vanilla until chocolate is melted. Then turn into a buttered 9 x9 pan and cool.