In a heavy pan add the water. Pour the sugar evenly over the top and place pan over medium heat swirling gently by the handle until the sugar dissolves and syrup is clear. Avoid letting the syrup boil until the sugar is completely dissolved.
When sugar is dissolved, increase the heat, cover tightly and boil for 2 minutes.
Uncover and continue to boil until it begins to darken around the edges. Gently swirl until the syrup turns deep amber.
Remove from heat and add the butter. Gently beat with a whisk until butter is incorporated.
Stir in heavy cream. If caramel sauce becomes lumpy set pan over low heat and stir until smooth. Remove from heat and add the vanilla and pinch of salt.
Cover and refrigerate up to one month. (When re-heating you can add some water if it is too thick.)