I make fudge every year. I always use the recipe on the marshmallow fluff jar. Here are a few in hints: Always make fudge on a clear day not cloudy,so my grandmother said. Also time carefully, start timing when the milk, sugar, butter mix hits a rapid boil and cook for four minutes exactly. Stir constantly but don't scrap the sides and bottom too often, just keep it moving. Have everything ready to dump in, open the jar of fluff, have chip bag open, measuring spoon out and vanilla bottle open. Have the pan ready for fudge to be poured in. Do all of this before putting heat to pan. If using an electric stove, get the pan off the burner at exactly four minutes of rapid boil. Your fudge is grainy because the sugar mixture did not cook long enough.