Well, a little over two years later I see your request and would like to give a little more insight to your dilema.

Other than being here in cold Michigan I love to make candy and other creations and have found a large dilema with the fudge that I may be able to help with.

The mistake everyone makes that the Mackinac Island fudge makers don't forget is the chemistry of cooking and everything in it's own time. Never stir after a boil until the temp. goes down or you will have grainy fudge every time.

Over medium heat, stir with a wooden spoon until sugar is dissolved and chocolate is melted. Increase heat and bring to a boil. Reduce heat to medium-low, cover, and boil for 3 minutes.

Remove the cover and attach a candy thermometer to the pot. Cook until the thermometer reads 234 degrees F.

Remove from the heat and add the remaining butter. Do not stir. Let the mixture cool for 10 minutes or until it drops to 130 degrees F.

Add vanilla and nuts, if desired, and mix until well-blended and the shiny texture becomes matte. Pour into the prepared pan. Let sit in cool dry area until firm.

Cut into 1-inch pieces and store in an airtight container for up to a week.

P.S. more facts at The Alaska Science Forum - The Pphysical Chemistry of Making Fudge. I hope this helps all us fellow fudge lovers, I know I had to learn the hard way.