In a small saucepan, combine the sugar and 2 tablespoons of water and bring to a boil. Using a wet pastry brush, wash down any crystals on the side of the pan. Boil over high heat until a deep amber caramel forms, about 6 minutes. Remove the saucepan from the heat and carefully whisk in the cream, butter, vanilla and a pinch of salt. Let the caramel cool to room temperature.