In a medium-sized saucepan add sugar and water. Cook on medium-low heat. Do not stir.
Sugar will dissolve and the mixture would start boiling vigorously. When the intensity of bubbles reduces, the colour changes to amber. (You can continue to cook until the colour reaches your desired preference but make sure to not cook when the appearance of bubbles stops). Switch off the flame.
Add hot heavy cream to the hot caramel in batches. Caramel will sputter so be careful. Mix till cream and caramel is well combined.
Add butter and salt to the mix. Cook on medium heat till the mix comes to a boil. Stir with a spatula to ensure every ingredient is properly combined. Switch off the heat.
Allow it to cool before further use. Cover tightly and store in the fridge for up to 1 month.