In a medium sized, heavy bottom sauce pan heat the sugar on medium to medium-high heat while stirring with a heat-proof wooden spoon or rubber spatula. Allow the sugar to first form clumps then turn into a thick amber sauce with no sugar clumps remaining.
Add the cut up butter while stirring, allowing the mixture to boil while the butter melts and combines with the sugar. Once combined, slowly pour in the cream. The mixture will bubble up - carefully stir the sauce as it boils for 1 to 2 minutes.
Remove the sauce from the heat and stir in the vanilla and salt until combined. Allow to cool before using.