Have at the ready: candy thermometer, lid for sauce pot, deep ice bath (I use my sink), and buttered 13x9 with a kitchen towel next to it.
Butter a 13x9 baking dish. Line lengthwise with buttered parchment. Line again the opposite direction with buttered parchment.
In a bowl, microwave cream and butter until hot. Add the vanilla bean after it is hot, and let stand in microwave.
In a heavy bottomed pot add water, corn syrup, and sugar. Cook on med-high until it boils. Cover for 1 minute. (This creates steam that will help to ensure all the sugar crystals melt and don't crystallize on the sides of the pan.)
Uncover, lower cooking temperature to medium. Cook until the sugar mixture reaches 320 degrees. This is when your sugar will caramelize and begin to change color.
When the sugar has become the color you like, add the hot cream/butter/vanilla bean mixture, slowly, 1/3 at a time. Stir only with your thermometer.
Continue to cook until temperature reaches 243 degrees.
Immediately dunk the bottom of your pot into the ice bath. This must be done rapidly, so as only to stop the cooking process but not cool your caramel so much that it won't pour. 1 or 2 seconds at the most.
Pour into buttered dish, making sure not to drip any water onto the caramel (this is where the kitchen towel comes in). Remove the vanilla bean with candy thermometer.
Cool at room temperature for 2-3 hours. Turn 13x9 upside down onto silpat or buttered parchment. Cut into bite-sized pieces, wrap in parchment or plastic wrap to keep. These freeze quite well.