Ensure that the butter and cream are at room temperature. The cream should be in a pourable container and ready to go when you need it.

In a medium pot set over medium low heat, add the sugar and water. Stir till blended.

Let it cook slowly, going through all the stages of bubbles etc.  If you find that a slight crust of hard sugar has formed on top towards the end, and it is already caramel coloured underneath, take a spoon and break up the crust and stir it back into the caramel underneath.  It will melt back into the sauce. This should take about 15-20 minutes. Don't rush it. This is what will give you the deep colour.

Once the sauce has foamed, and stirring helps the foam to reduce (it will turn a lovely shade of copper), remove the pot from the heat and add the cream (stand away from the pot) 

Stir regularly until the mixture is smooth and turned the most beautiful whiskey or copper colour.

Immediately add in the butter and bourbon.  Stir till butter is melted and everything is smooth.

Stir through the salt Let cool and serve.  Or:

Leave to cool before placing it into the container you will store it in.  I use a glass container (a Weck jar with a a plastic lid)  Once cooled, you can store it in the fridge.

When you are ready to use it in a recipe, bring it to room temperature, or even reheat the amount you need in a small pot set over low heat.