Combine sugar and water in a heavy bottomed pan.
1 cup Tightly packed Brown Sugar, Water
Bring to boil, stirring continuously. Cook the sugar mixture till it starts bubbling.
Add soft butter and let it melt and mix in the sugar mixture. Bring it to boil. Add salt in this step when using unsalted butter.
½ cup Butter
Remove the pan from heat let it cool it for a minute. Keep stirring not to further cook the sugar.
Add vanilla essence to cream and mix well.
2 tsp Vanilla Essence
Add cream to the mixture stirring the mixture. Add cream slowly to the mixture, as sugar can splatter when adding the cold cream to hot sugar mixture.
1 tsp Salt
Return the pan to heat and stir continuously for next 2 minutes or till the mixture reaches 240°F or 115°C.
Let it cool a bit and transfer to a heat-proof bowl and microwave safe bowl.