I'm 47 and have made this recipe forever and my mom made it when I was little. I prefer a fudge that is firm enough that it does not need refrigerated. Once I hit the 234 degree soft boil point, I cook it an additional 4-5 minutes. I add the marshamallow and chocolate and mix a little at a time, but I keep the pot on medium heat the whole time. Once I get the vanilla and nuts in, I use my mixer and whip it to mix it thoroughly. I can't work fast enough by hand. Once I pour it into my pan and even it out, I let it cool overnight at room temp. Chill it for about an hour before cutting it to get clean, perfect squares.