Preheat oven to 150⁰C (300⁰F). Put on a jug of water to boil and set aside.
Custards: Place egg yolks in a large bowl and lightly whisk till smooth. Set aside.
In a medium sized saucepan and over a medium heat, heat the muscovado sugar, milk, cream, salt and the vanilla bean and seeds (or vanilla extract). Stir until sugar starts to dissolve and the milk is steaming and tiny bubbles have formed along the edges, but do not boil. Remove from heat. Cover and keep warm.
In a heavy based medium saucepan, combine the caster sugar and water. Over a low heat, stir the sugar and water until the sugar dissolves. Then stop stirring and turn up heat to medium/high until the sugar comes to a steady simmering boil. The bubbles will be fast and furious for a while, then will calm down and the bubbles will get fat and lazy. If any sugar crystals form on the side of the pan, brush them down with a bit of water using a pastry brush. Keep an eye on the mixture; it will turn colour initially to light amber, then a medium amber. Keep going until it turns the colour of a copper penny (see image below).
Immediately take off the heat and carefully add ¼ cup of the hot cream mixture, whisking until combined. Slowly add the rest, whisking as you go. Pour the caramel cream into the bowl of whisked yolks in a slow, steady stream whisking the mixture continuously (don’t over-whisk, as you don’t want to aerate it). Strain the custard through a fine strainer (or sieve) into a pitcher. Skim off any foam or bubbles on top.
Pour the custard carefully into the ramekins, leaving ½ inch at the top of each. Place ramekins in a roasting pan and carefully fill the pan with hot water until it comes halfway up their sides. Place a large piece of foil over the pan and tuck lightly around the edges. Bake in the oven for 40-50 minutes until set. When done, the edges will be firm, but the centre will jiggle when the custard is gently shaken (the reason you take it out at this stage, is that it continues to set as it cools). Remove from the pan and let cool. When cool, refrigerate uncovered (to keep its burnished color) for several hours or overnight.
Caramel Sauce: In a medium saucepan, mix 1 cup caster sugar with 2 tablespoons of water. Over a low heat, stir the sugar and water until the sugar dissolves. Then stop stirring and turn up heat to medium/high until the sugar comes to a steady simmering boil. The bubbles will be fast and furious for a while, then will calm down and the bubbles will get fat and lazy. If any sugar crystals form on the side of the pan, brush them down with a bit of water using a pastry brush. Keep an eye on the mixture; it will turn colour initially to light amber, then a medium amber. Keep going until it turns the colour of a copper penny (see image below). Immediately take it off the heat and very carefully add the hot water and whisk until smooth (should the mixture seize up and become toffee, don’t panic – just return it to the heat and keep stirring and it will liquify again). Add the vanilla extract. Let it cool.
Assembly: Take the custards out of the fridge about 30 minutes prior to serving. Dollop a small amount of the whipped crème fraiche on top (a small amount goes a long way) and drizzle generously with caramel sauce (you’ll keep adding more, trust me!).