Penuche Fudge
["1 lb. light brown sugar", "3/4 c. heavy cream", "1/2 stick butter", "1 c. walnuts (optional)", "1 tsp. vanilla", "1/2 jar Marshmallow Fluff (7 1/2 oz. size jar)"]
["Put sugar, cream and butter into heavy saucepan and cook until it forms a soft ball when tried in cold water (or use candy thermometer and cook to soft ball stage, 236\u00b0 to 238\u00b0)."]
["light brown sugar", "heavy cream", "butter", "walnuts", "vanilla", "Marshmallow"]