Stirred Custard
Cooking Skills: Eggs 2
Chapter 2 · Stirred Custard
Skill goal
Thicken milk with egg yolks into a smooth custard, without letting it curdle.
Shopping list for this chapter
The basics
Real custard is milk thickened by egg yolks, and it's one of the best examples of what heat does to an egg. The yolk proteins start to thicken at about 70°C and the custard turns thick and glossy at about 80°C, but above about 85°C they clump and the custard curdles into scrambled egg. The whole skill is staying in that narrow window.
| Temperature | What happens |
|---|---|
| Below 70°C | Thin, runny, not yet cooked |
| 70 to 80°C | Thickening; coats the back of a spoon at about 78 to 82°C |
| Above 85°C | Curdling: grainy, scrambled-egg texture |
| Boiling | Definitely scrambled |
Method in brief
- Warm the milk in a pan until steaming, not boiling.
- Whisk the yolks with the sugar (and cornflour if you use it) in a bowl until pale and smooth.
- Temper: pour the hot milk onto the yolks in a thin stream, whisking all the time, so the yolks warm up gradually instead of being shocked.
- Return to the pan over the lowest heat and stir constantly with a wooden spoon or silicone spatula, scraping the base. Cook for 5 to 8 minutes until the custard coats the back of the spoon: run a finger through it and the line should stay.
- Pour at once into a cold jug through a sieve. Stop the cooking by getting it out of the hot pan. Stir in the vanilla.
A thermometer helps
A digital probe thermometer makes custard much easier: take it off the heat at 80 to 82°C. No thermometer: the coat-the-spoon test is just as good once you've done it a couple of times.
Try it
Level 1 · Start here
Cornflour-stabilised custard
A little cornflour stops the yolks curdling and makes the custard forgiving. Start here, then try without it.
Ingredients (2 portions)
- 250 ml whole or semi-skimmed milk
- 2 medium egg yolks (keep the whites for chapter 6)
- 25 g caster sugar
- 1 tsp cornflour
- ½ tsp vanilla extract
- Heat the milk in a small pan until steaming.
- Whisk the yolks, sugar and cornflour in a bowl until pale and smooth.
- Pour the hot milk onto the yolk mixture in a thin stream, whisking.
- Return to the pan over low heat and stir constantly for 3 to 5 minutes, until the custard thickens and coats the back of a spoon. Don't let it boil.
- Strain into a jug, stir in the vanilla and serve warm. Press cling film directly onto the surface if you are keeping it, to stop a skin forming.
Level 2 · Classic
Classic custard (crème anglaise)
The pouring custard the chefs make: yolks, sugar and milk only. It tastes cleaner, but it has no safety net. Follow the heat advice carefully.
Ingredients (3 portions)
- 250 ml whole milk
- 3 medium egg yolks
- 30 g caster sugar
- 1 tsp vanilla extract (or half a vanilla pod, split)
- If you use a vanilla pod, put it in the milk, bring it to steaming and leave to infuse for 10 minutes; otherwise just heat the milk.
- Whisk the yolks and sugar until pale. Pour the hot milk onto them gradually, whisking.
- Return to the pan over the lowest heat and stir constantly in a figure of eight, scraping the base. After 6 to 8 minutes it should coat the back of a spoon, at about 80°C.
- Immediately pour through a sieve into a cold jug and stir for 30 seconds to cool it. Add the vanilla extract if you didn't use a pod.
If it curdles
Take the pan off the heat at once, pour into a blender or use a stick blender for 20 seconds, then sieve. It will often smooth out. Failing that, it makes a very good scrambled-egg sauce for the cook.
Level 2 · Pudding
Baked apple with custard
Use your custard for what it is for: a warm fruit pudding with real custard on top. A small portion of custard goes a long way.
Ingredients (1 portion)
- 1 large cooking or eating apple
- 1 tsp raisins or sultanas
- ½ tsp ground cinnamon
- 1 tsp brown sugar or honey
- 80 ml of the classic or cornflour custard from this chapter (about one third of a batch)
- Heat the oven to 180°C fan (200°C conventional, gas 6). Core the apple and score a line round its middle (this stops the skin splitting).
- Stand it in a small ovenproof dish. Fill the hole with the raisins, cinnamon and sugar, and add a splash of water to the dish.
- Bake for 25 to 30 minutes, until soft when you press it with a knife.
- Pour the warm custard over the apple and serve.
Level 3 · Treat
Custard ice cream (stir-freeze)
A rich custard base frozen in a tub, stirred a few times to break up the ice crystals. No machine needed. This is the method the Ice Cream course will build on.
Ingredients (4 portions)
- 250 ml whole milk
- 150 ml double cream
- 4 medium egg yolks
- 60 g caster sugar
- 1 tsp vanilla extract
- Heat the milk and cream until steaming. Whisk the yolks and sugar until pale, pour on the hot milk gradually, then cook gently in the pan as for the classic custard until it coats the back of a spoon (about 8 minutes).
- Strain into a clean bowl, stir in the vanilla, and cool quickly by standing the bowl in a sink of cold water.
- Chill in the fridge for at least 3 hours (overnight is better).
- Pour into a shallow freezer-proof tub. Freeze for 1 hour, then beat well with a fork or a whisk to break up the ice crystals. Repeat every hour 3 times, then freeze until firm.
- Take it out of the freezer 10 minutes before serving.
Lighter swap
Use semi-skimmed milk and single cream instead. It won't be as smooth, but it's still good.
Experiments
Experiment
Cornflour or none
How much does the cornflour help, and does it change the taste?
- Make the cornflour custard and the classic custard, side by side.
- Take each off the heat as soon as it coats the spoon.
- Taste both when they have cooled slightly.
Look for: How easy each was to cook without curdling, and whether the cornflour version feels thicker or tastes floury.
Experiment
Low heat vs medium heat
See what curdling looks like, on purpose.
- Make two small batches of the classic custard. Cook one on the lowest heat, and one on medium heat.
- Take the temperature if you have a thermometer.
Look for: The medium-heat custard curdles in a few seconds. Now you know the warning signs: grainy streaks on the spoon.
Experiment
Sieved or not
Does straining the custard matter?
- Pour half the classic custard straight into a jug, and the other half through a sieve.
- Compare the texture on the tongue.
Look for: Tiny bits of cooked egg that you can only feel when unsieved. A sieve is cheap insurance.
Tasting notes
| What I tried | Method or heat | What I saw | What I thought | Will I do it again? |
|---|---|---|---|---|
| Cornflour custard | ||||
| Classic custard | ||||
| Baked apple with custard | ||||
| Custard ice cream | ||||
| Low vs medium heat | ||||
| Sieved vs unsieved |
Troubleshooting
| Problem | Likely cause | What to do |
|---|---|---|
| Custard curdled (grainy) | Too hot, or too quick on the heat | Take off the heat, blend and sieve; use lower heat next time |
| Custard too thin | Not cooked long enough | Cook a little longer, stirring, until it coats the spoon |
| Skin on top | Left uncovered as it cooled | Press cling film onto the surface |
| Eggy taste | Overcooked, or old eggs | Use fresh eggs and a lower heat |
| Lumps of cooked egg | Yolks added to hot milk too fast | Add the milk in a thin stream, whisking all the time |
| Ice cream icy | Not stirred enough, or base too thin | Beat well each hour, and use full-fat milk and cream |
Food safety: custard
Custard is a perfect place for bacteria to grow. Cook it to about 80°C, cool it quickly (stand the pan in cold water), refrigerate within 2 hours and use within 2 days. Reheat gently until steaming hot. Don't eat uncooked custard base, or ice cream made from a base that wasn't cooked, if you're pregnant, elderly or very young.
Checkpoint: can you do this now?
- I can tell when custard coats the back of a spoon.
- I know why custard curdles and how to rescue it.
- I can temper yolks by adding hot milk slowly.
- I have a use for the egg whites I saved.
- I know which custard I prefer: cornflour or classic.
Next chapter
Cooking Skills: Eggs 2, chapter 3 is Baked Custards: setting custard gently in the oven, from egg custard to crème caramel.