In a medium saucepan heat the sugar over medium heat, stirring constantly with a silicon or rubber spatula that can handle high heat. The sugar will start turning a caramel brown. Make sure you are stirring frequently to prevent burning.

Once sugar is completely melted, immediately stir in the butter until melted and combined. This is going to cause a vigorous reaction and the cold butter will drastically cool the and bubble a lot. Remove it from the heat to keep the boiling down if it gets too vigorous. Add it back to the heat and stir until all of the butter has melted.

After the butter has melted continue to stir constantly while slowly pouring in the heavy cream. Just like the butter it will cause the mixture to bubble vigorously. Once the cream has been completely mixed stop stirring and let the caramel sauce cook for 2 minutes. It will boil to the top.

Remove from heat and stir in the salt and bourbon. Allow to cool for 10 minutes before pouring into another container. Allow to cool until the container is cool enough to hold before using.