Preheat the oven to 160C / 320F / 140C fan forced. Place 4 ramekins (notes) in a flat bottomed baking tray with high sides.
Warm the cream in the microwave for 30 seconds and set aside - just so it's not cold.
Place the sugar and water in a heavy based stainless steel saucepan over low heat (notes). Heat, swirling from time to time until all the sugar is dissolved in the caramel.
Let it come to a bubble then continue to cook, swirling every so often until it turns amber in colour.
Carefully pour in the cream so that it doesn't splash, and stir with a spatula. Keep stirring over low heat until the caramel melts back into the cream so you have a smooth caramel cream. Remove from heat and set aside.
In a medium bowl, whisk the egg yolks until very pale.
Slowly pour the hot cream mixture into the egg yolks while gently stirring with a whisk at the same time. Make sure to pour slowly so the sudden heat doesn't scramble the eggs.
Add the salt and stir it through.
Strain the mixture into a pouring jug then pour evenly into the ramekins.
Now pour hot (not boiling) water into the baking dish, around the outside of the ramekins to halfway up their sides.
Bake for 45 minutes or until the centres look just set (notes).
Very carefully lift the ramekins out of the baking dish and set aside to cool for 15 minutes before covering with plastic wrap and placing in the fridge to chill for 3-4 hours.
Caster / superfine sugar (not powdered) is best as it will dissolve quicker. If you can only use regular white granulated sugar, just keep the heat a little lower so that it is mostly dissolved before it starts to bubble.
All ovens are different, the size or thickness of the ramekins, how hot the custard was before you put it in the oven are all things that can affect baking time. I generally cook them for 45 minutes, then check every 5 minutes thereafter.
You'll know they are done, when you give them a gentle shake and they have a slight wobble in the centre but not like there is liquid under the surface - think jelly.
Pots de creme can be made up to 2 days in advance. If adding a sugar topping to turn them into a salted caramel creme brulee, leave that until just before serving.