Ingredient

Crème anglaise

Crème anglaise is a pouring custard of egg yolk, sugar, milk and cream, thickened by heat alone with no starch. That absence of starch is what makes it delicate and what makes it fail: the yolk proteins that thicken it are the same ones that, a little further on, turn it into sweet scrambled egg.

The window, and why it is narrow

Egg yolk proteins are coiled up. As they warm they unfold and begin to link to one another, forming a loose network that traps the liquid — and that network is what thickens the custard.

Keep going and those same links tighten. The network contracts, squeezes out the liquid it was holding, and you have solid curds in thin liquid. That is curdling, and there is no un-doing it.

The gap between "thick enough" and "scrambled" is a matter of a few degrees, which is why crème anglaise has its reputation. Two things widen that window usefully. Sugar gets between the proteins and raises the temperature at which they set — a custard with plenty of sugar is more forgiving than a barely sweetened one. And gentle, even heat gives you time to see it coming.

Cornflour would make it foolproof and would also make it a different sauce — crème pâtissière rather than crème anglaise. A teaspoon of cornflour is entirely legitimate as insurance and is what many home cooks quietly do.

The method

1. Warm milk and cream in a pan with a split vanilla pod or other flavouring, and bring it just to the point of steaming. Take it off and let it infuse.
2. Whisk egg yolks with sugar until pale and slightly thickened. This is not just mixing — the sugar dissolving into the yolk protects it.
3. Temper: pour the hot milk onto the yolks slowly, whisking constantly. Adding it all at once cooks the yolks on contact.
4. Return the mixture to the pan over a low heat. A heavy-based pan matters here.
5. Stir constantly with a wooden spoon or spatula, in a figure of eight, keeping the base and corners moving. Do not whisk — foam makes it impossible to see the thickening.
6. Watch for it to thicken enough to coat the back of the spoon. Draw a finger through it: if the line holds clean and the custard does not run back in, it is done.
7. Take it off the heat immediately and strain it into a cold bowl. Straining catches any threads of egg and stops the residual pan heat carrying it further.
8. Cool it with cling film pressed onto the surface if you want no skin.

Rescuing and preventing

• If it starts to catch, pull it off the heat instantly and keep stirring. The residual heat in the pan continues cooking it, so getting it into a cold bowl fast matters.
• If it has just begun to curdle, blend it hard with a stick blender, or shake it in a sealed jar. This breaks the curds up and will often rescue it, though the texture is never quite as good.
• If it has properly scrambled, it is finished. Strain it and use the liquid, or start again.
• Use a bain-marie if you are nervous. Slower, much harder to overshoot.
• Add a teaspoon of cornflour to the yolks and sugar. It makes curdling almost impossible and slightly changes the character.
• Have the strainer and the cold bowl ready before you start. The moment you need them you will not have time to find them.
• A thermometer removes the guesswork entirely, if you have one.

The custard family

Crème anglaise

Pouring custard. Egg yolk, no starch. Thin enough to pour, delicate, easy to curdle.

Crème pâtissière

Pastry cream. Egg yolk plus flour or cornflour. Thick enough to pipe, must be boiled, and cannot curdle in the same way.

Custard powder

Cornflour and colouring, no egg. Thickens by starch alone. Different in flavour and far more robust.

Baked custard

Set in the oven rather than on the hob — crème caramel, crème brûlée, custard tart. Same proteins, gentler heat, and a bain-marie doing the moderating.

Ice cream base

Crème anglaise churned. This is why so many ice cream recipes begin with the same instructions.

Sabayon / zabaglione

Yolks, sugar and wine whisked over heat into a foam. Related proteins, aerated rather than thickened.

Common questions