Add the sugar to a heavy bottom pan and keep this on medium high heat. The sugar will start to clump and then eventually start melting. Shake the pan in a circular motion or use a whisk to mix the mixture.
Once the sugar starts melting, turn the heat to medium. The melted sugar should turn from light amber color to deep amber color. Keep rotating the pan as it won't take the sugar to go from done to burnt in few seconds. Add the butter, mix well, turn off the heat and then pour the heavy cream and whisk everything well again. Stir in the salt.
Let this cool down for 15-20 minutes before transferring into a glass jar.
Regrigerate: Slightly warm the sauce before serving.
Perfect as a topping for ice-cream, frostings, cakes.