In a medium saucepan add sugar and water and stir to combine.
Cook over medium heat, about 3-5 minutes, stirring until the sugar dissolves. Once the liquid is clear and starts to bubble, continue cooking on medium until the mixture reaches 338-350 ℉, about 10-15 minutes. During this time not stir the mixture or it can cause the caramel to get grainy.
Be sure to wipe down any sugar crystals form the sides of the pan using a pastry brush dipped in water. You can also place the lid on the pot for a few minutes and allow the steam to dissolve any sugar crystals.
Once the sugar hits the correct temperature it will have have thickened up a bit and turned a golden amber color.
Immediately remove from heat and stir in the butter. It will bubble up quite a bit, this is totally normal, just continue stirring.
Then, slowly add in the cream and continue mixing until it has fully incorporated.
Stir in vanilla and salt.
The sauce will thicken as it cools. Once it’s cooled down it’s ready to use on your favorite dessert or be stored in an airtight container for later use.