Add the water to a stainless steel saucepan without non-stick coating (the high temperatures involved in making caramel can damage non-stick surfaces). Then carefully add the sugar into the middle of the pot making sure you don't get sugar crystals on the sides of the pot. Don't stir the sugar.

Scrape the vanilla beans from the pod into a small saucepan, then add the pod along with the cream. Heat over low heat while you make the caramel.

Cover the sugar water with a lid and bring it to a boil over high heat.

Remove the lid and continue letting the mixture boil until you see it start to change color. Turn down the heat to medium and then insert a candy thermometer or use a digital instant read thermometer with a range that exceeds 330F to monitor the temperature until the caramel hits 330 degrees F.

The moment the caramel hits 330 degrees F, turn off the heat and slowly start pouring the cream into the caramelized sugar while whisking. Be very careful as the caramel will bubble up furiously and it is extremely hot! Keep adding and whisking the cream into the caramel until it is all incorporated (you can discard the vanilla pod).

Whisk in the butter and salt and let the caramel sauce cool before pouring it into a container to store.