In a heavy-bottomed saucepan, combine the granulated sugar and water. Stir gently until the sugar is fully dissolved.
Place the saucepan over medium heat. Allow the sugar mixture to come to a boil without stirring. You can gently swirl the pan to ensure even heating.
As the mixture begins to boil, keep a close eye on it. After a few minutes, it will start to turn a golden amber color.
Once the caramel has reached a deep amber color, remove it from the heat. Carefully whisk in the salted butter until fully incorporated.
Gradually pour in the heavy cream while whisking continuously. If the sauce seizes up, return it to low heat and stir until smooth.
Stir in the sea salt to enhance the flavor. Taste the sauce and adjust the salt if desired.
Let the caramel sauce cool for a few minutes before transferring it to a heat-resistant container. It will thicken as it cools.
