In a heavy-bottomed saucepan, combine the sugar and water over medium-low heat until the sugar dissolves.

Increase the heat and bring to a boil, without stirring.

Use a wet pastry brush to wash down any crystals on the side of the pan.

Boil until the syrup is a deep amber color, about 5 minutes.

Remove the sugar from the heat and carefully whisk in the heavy cream.

The mixture will bubble.

Stir in the unsalted butter, and salt.

Transfer the caramel to a dish and cool.