Step 1

Combine the sugar and water in a medium-sized heavy-bottomed pot over medium heat. Stir the mixture with a wooden spoon or heat-resistant rubber spatula, so it's thoroughly combined. Cook for 3-4 minutes until the sugar dissolves and turns clear. It will also start to bubble. Once this happens, don't stir again.

Step 2

Allow the liquid to bubble. Swirl the pan occasionally and brush down the sides to prevent crystallization of the sugar. The sugar will begin to clump but continue swirling until the mixture thickens and turns a deep amber color. This will take somewhere between 8-12 minutes.

Step 3

Add the butter slices and mix until completely melted. NOTE: the caramel will bubble up, so be careful and continue to stir.

Step 4

Remove the pan from the heat and slowly add heavy cream while stirring continuously. Be sure to keep stirring until all the cream has been incorporated into the mixture. Finally, stir in the vanilla and sea salt until it fully dissolves. This should take about one minute or so in total.