Combine the sugar and water in a medium sized saucepan over low heat, whisking until the sugar has dissolved. This takes about 3-5 minutes.
Add the butter to the sugar water and whisk while it melts.
When the butter has melted, bring the mixture to a low boil.
Stop whisking! Allow the mixture to boil for 10-15 minutes, until it develops a deep copper color. Don’t walk away from the stove, you want to watch it so it doesn’t burn. The color will change quickly.
Remove the pan from the heat.
Carefully and quickly whisk in the cream. Be careful, as the mixture will splatter a little as you add the cream into the pan.
Add in the vanilla extract and the salt and whisk to combine.
Transfer to a glass jar (I like using a mason jar), and allow to cool to room temperature.
Place the lid on and store in the fridge.
Notes
When the caramel has cooled to room temperature, you can store it in the fridge for up to 1 month in an air-tight glass container with lid. The caramel solidifies as it cools, but you can easily scoop out portions and reheat it in the microwave to make it liquidy again.