In a 2 quart sauce pan, add sugar and water and stir to combine. Turn on heat to medium.
Allow sugar to come to a boil, give a quick stir, then continue to let it boil. You'll notice the sugar begins to darken in color a bit.
Continue to stir every once in a while as the sugar darkens. Once the sugar darkens, add the butter and stir to combine (be careful, as caramel sauce can bubble up and steam once you add the butter).
Remove pan from heat and stir in heavy cream (again, being careful, as caramel sauce can bubble up and steam once you add the cream).
When your sauce is silky and smooth, add salt and stir to combine.
Allow caramel to cool completely. Caramel will thicken as it cools.
Use immediately, or transfer to a jar with lid and refrigerate until ready to use.