I got this recipe from the sweetest 80+ year old man, named Mr. Ryan, when I worked as a bank teller for a while. He lost his wife, the love of his life, and he would come to the bank just to talk or to give us fudge. I've never met a sweeter person and I've never had better fudge. I would rave about his fudge and one day he brought me the hand written recipe. It's hard to read and kind of out of order in places, but it means the world to me. "Made with Love" is written at the bottom. I have since moved to a different state and lost touch but his memory lives on in my heart.
In sauce pan combine sugar, margarine, and evaporated milk. Cook on high until mixture boils. Turn down to medium heat and stir constantly for 7 minutes. I use a wooden spoon for this.
Remove from heat. Add marshmallow, chocolate, and vanilla. Transfer to an electric mixer. Mix 2 minutes. Everything should be completely melted and incorporated. Pour into prepared pan. Shake to level and put in refrigerator to cool.
Mr Ryan says "You can add walnuts" but I have never done this and I don't know how much would be good.