I've always found custard pretty tricky to make the conventional way - a lot can go wrong, and it takes quite a bit of practice to get right. In this recipe, I'll show you the traditional way, and also a foolproof method using a sous vide machine.
Prep the Custard
If you are using a vanilla pod, slit it open longways and scrape out the seeds with the back of a knife. Keep the pod. Separate the egg yolks into a bowl and whisk them briefly to break them up. Whisk in the sugar and the cornflour.
Cook the Custard the Traditional Way
Add the milk and cream to a small saucepan and heat up to simmering point. Be careful not to overheat it because it can curdle. Add the vanilla pod and seeds, or vanilla essence if you are using that. When you can just see some movement on top of the milk/cream mixture, remove it from the heat and fish out the vanilla pod. Add the milk/cream mixture to the eggs, a little bit at a time. Whisk it in well before adding more. When it's all mixed, put it back in the pan and heat it again, stirring constantly. When you feel the custard start to thicken and it coats the back of a spoon, you have achieved custard! Take it off the heat immediately.
Cook Custard Sous Vide
Set your sous vide machine to heat the water up to 82°C (180°F). Mix all the ingredients together and pour into a zip-lock bag. When the water has come up to temperature, place the bag in, let the water squeeze out the air and zip it closed. Cook it for 20 minutes, then remove it from the water. Massage the bag a little with your fingers (be careful, it will be hot!), pour it into a jug or gravy boat and serve.
• 120 ml milk • 120 ml double (heavy) cream • 60 grams sugar • 3 egg yolks • 1 vanilla pod
PLUS You can use half a teaspoon of vanilla essence (or just use vanilla-infused sugar) if you don't have a vanilla pod. If you're doing it the traditional way, you might want a teaspoon of cornflour (cornstarch), And maybe use more milk than cream.