In a 3-quart saucepan, combine sugar, salt, butter and milk; bring to a boil over medium heat, stirring constantly. Continue cooking, stirring constantly, for 6 minutes.
Remove from heat; add remaining ingredients, stirring until chocolate chips melt.
Pour into buttered 9×13-inch baking pan. Refrigerate, covered, several hours, then cut into 1-inch squares. Refrigerate or freeze until needed.