Place the water and sugar in a saucepan and heat on medium high heat, swirling the pan to get the sugar wet and to encourage it to dissolve and melt. Don't stir.

Keep cooking, swirling once or twice for 5-10 minutes until the mix is a lovely caramel colour. Go longer if you want a darker shade but be very careful, blink and you'll have a burnt mess!

When you're happy with the caramel, take it off the heat and whisk in the butter gently until completely melted.

Add the salt, stir well, with a wooden spoon.

Finally, stir in the cream and vanilla. Taste. Add more salt if you like it saltier.

It will keep in a clean container, covered, in the fridge, for 2 weeks, easily.