Crème Anglaise
What it is
A thin, pourable vanilla custard sauce — literally "English cream." It is thickened by egg yolks alone, with no starch, to a delicate coating consistency. It is also, before churning, exactly the base for French-style custard ice cream, and the foundation of bavarois and many plated desserts.
The science
Egg-yolk proteins (livetins and lipoproteins) denature and gently network as they heat, raising viscosity. Thickening begins around 70 °C; the working target is 77–82 °C (170–180 °F). Cross above roughly 82–85 °C and the proteins over-coagulate — bonding too tightly, expelling water, and "scrambling" the sauce into curds. The whole craft is hitting enough denaturation to thicken without tipping into coagulation. Sugar is protective: it interferes with protein-to-protein bonding and raises the coagulation temperature, widening your safety margin (which is why yolks are whisked with sugar before heat). The doneness benchmark is nappe — French for "to coat": the cooked sauce films the back of a spoon, and a finger drawn through leaves a clean, un-flooding channel. Vanilla is infused by splitting and scraping a bean into scalded dairy and steeping; vanillin and its companion aromatics are both fat- and water-soluble, and the pod itself carries more flavor than the seeds, so both go in.
How it's made
Scald milk (or milk and cream) with the split vanilla and let it steep. Whisk yolks with sugar until pale — blanchir — which also shields the yolks from curdling on first contact with heat. Temper: dribble the hot dairy into the yolks while whisking, raising their temperature gradually, then return everything to the pot. Cook over low-to-medium heat, stirring constantly with a spatula in a figure-eight that scrapes the bottom, until you reach 77–82 °C or the nappe. Strain immediately and chill over an ice bath to halt carryover. A thermometer makes this nearly foolproof; the nappe test and watching the surface foam subside are the traditional cues.
Regional variations
Crème anglaise is a French foundation named for the English custard tradition it descends from. English "proper custard" is a close, often slightly thicker relative — while Bird's custard (Alfred Bird, 1837) is a different product entirely: a cornflour-based, egg-free imitation invented because Bird's wife couldn't eat eggs, and therefore technically closer to a thin pastry cream than to true crème anglaise. Italy's crema inglese mirrors the French; its zabaglione is a separate animal (egg yolks whipped with Marsala and sugar, no milk). Crème anglaise is a "mother" sauce of the dessert world — parent to ice cream, bavarois, and the pool beneath floating islands.
Cultural & historical context
Custards are ancient — Roman cooks bound egg-and-milk mixtures, and medieval European "custarde" filled open pastry shells. The French codified the stirred custard into the precise, thermometer-friendly technique recognized today, and through Carême and Escoffier it became infrastructure for the entire patisserie.
Reference notes
Cross-link to Crème Pâtissière (its starch-bound sibling), custard ice cream, sabayon / zabaglione, crème brûlée (its baked cousin), the egg-coagulation and tempering technique pages, and vanilla. Pairs with chocolate, coffee, berries, stone fruit, and caramel.
When to use
As a pourable sauce beneath or beside cake, soufflé, poached fruit, or île flottante; as the custard ice-cream base; as the liquid heart of bavarian cream. Choose it over pastry cream whenever you want a thin, pourable, starch-free custard with clean texture and no body to hold a shape.
What goes wrong
Scrambling from overheating — strain at once; a stick-blender can sometimes rescue a slightly broken sauce; prevention is low heat, a thermometer, constant motion, and sugar. Under-thickening leaves a raw, eggy thinness. Skin forms on standing — press plastic to the surface. Lumps appear if you add hot dairy to cold yolks too fast, skipping the temper.