Set cold tablespoon of butter in large bowl (glass or non-reactive metal) and set aside.
Line a 8-inch square baking pan with foil lined parchment paper. Lightly grease the parchment side with butter.
In a medium sized heavy saucepan, combine remaining ingredients. Cook over medium low heat, stirring constantly, until the sugar fully dissolves. This will take about 10 minutes.
Increase heat to medium to bring mixture to a boil. Do not stir. Insert a thermometer. Allow mixture to continue bubbling. Occasionally wash down sides of pot with water using a silicon brush to avoid crystals from building up. Cook until the fudge meets the soft ball stage of 238 degrees F. This should take about 10-15 minutes.
As soon as the fudge hits the soft ball temperature, pour it into the bowl with the tablespoon of butter. Do not scrape the bottom of the pot as there may be over cooked parts you do not want in your fudge. Do not stir the fudge when it hits the bowl. Simply allow it to cool undisturbed with the thermometer in place. When the fudge reaches 110 degrees F, start to stir the mixture. After about 5 minutes of stirring, the fudge will lighten in color and start to lose it's sheen. Remove vanilla bean pods and pour into prepared pan. Quickly spread fudge to make an even layer, as it will set quickly.
Allow to cool in pan at least one hour.
To cut, lift the foil lined parchment and transfer the fudge to a cutting board. Cut into 36 bite-sized pieces.
Store in an air tight container at room temperature. Fudge can also be frozen for longer storage.