In a pan mix the sugar and water, until combined.

Heat the sugar water mixture and let it boil. Don't stir this during boil, and let it turn a dark amber brown.

Once it is a dark colour, turn off the heat. Pour in the cream (careful of the splatter) and stir quickly to remove the lumps. Stir in the vanilla too.

After a minute or two slowly stir in the butter. Place into a separate dish.

This will keep in the fridge for at least a week. Top with some flakes of sea salt to taste!