Add the sugar to a medium sized saucepan set over medium heat. Stir occasionally until the sugar begins to melt, then stir constantly until the sugar is completely melted and has turned to a deep amber color.
Add in the butter and whisk until the mixture is smooth.
Take the mixture off of the heat, and slowly whisk in the heavy cream until it is completely incorporated into the caramel. Whisk in the salt and vanilla.
Allow the caramel to cool down in the fridge to thicken up before serving. Enjoy with apples, apple pie, brownies, cheesecake, carmelitas, coffee - or by the spoonful!