Custard Base
Three egg yolks, 200 g cream, and sugar — the 3:200:60 ratio that underlies crème brûlée, ice cream, and tarts, built on the controlled coagulation of egg yolk proteins.
Ingredients
- 3 egg yolks (from large eggs, about 60 g total yolk)
- 200 g heavy cream (35% fat minimum)
- 60 g white sugar
- 1 vanilla pod, split and scraped (or 1 tsp pure vanilla extract)
- Pinch of fine sea salt
Steps
Heat the cream with the vanilla pod (pod and scraped seeds both go in) in a small heavy saucepan over medium-low heat. Bring to a bare simmer — small bubbles around the rim, steam rising, about 80°C. Do not boil. Remove from heat and let the vanilla steep for 5 minutes. If using extract, skip the steeping; add at the end.
In a medium bowl, whisk together the egg yolks, sugar, and pinch of salt until the mixture is pale and slightly thickened — about 1 minute of vigorous whisking. This is called 'ribboning.' The sugar dissolves into the yolks and begins to denature the proteins slightly, making them more heat-stable in the next step.
Temper the yolk mixture: ladle the warm cream in slowly — in a thin, steady stream — while whisking constantly. Do not rush this. Adding hot cream too fast will scramble the yolks. The goal is to gradually raise the yolk temperature from room temperature to about 60°C before the full mixture goes back on the heat.
Pour the tempered mixture back into the saucepan. Cook over very low heat, stirring constantly with a heatproof spatula or wooden spoon, using a figure-eight or sweep motion that covers the entire bottom of the pan. The custard will gradually thicken. This happens between 72 and 82°C — the zone where yolk proteins partially coagulate without fully setting.
Watch for the moment the custard coats the spatula and a finger drawn across the back leaves a clean line that does not flood back. Pull off the heat immediately. This is called 'à la nappe' (coating consistency). Strain through a fine-mesh strainer into a clean bowl. If using vanilla extract, stir it in now. Cool over an ice bath, stirring occasionally, to stop the carry-over cooking.
Tools you'll want
- · Tri-ply stainless saucepan (1.5–2 qt / 18cm)
- · Balloon whisk (24cm / 11-inch)
- · Sauce strainer (chinois or perforated, 19–25cm)
- · Digital kitchen scale (gram precision)
- · Instant-read digital thermometer
Why this works
A custard is egg yolks cooked in liquid — very gently, at a precise temperature. The entire technique exists to navigate a narrow window: above 72°C, yolk proteins begin to coagulate and thicken the mixture; above 85°C, they tighten too far and the custard curdles into a grainy, sweet scrambled egg. Everything in this recipe is designed to stay inside that window.
Egg yolks contain several proteins that behave differently at different temperatures. Livetins coagulate first, around 72°C; phosvitin and the lipoproteins follow. The gradual stiffening of these proteins is what thickens the custard. Sugar — dissolved into the yolks before heat is applied — raises the coagulation temperature slightly (by about 3–5°C) and gives you a larger working window. This is why the ribboning step (whisking yolks with sugar) matters: you are not just incorporating the sugar, you are chemically adjusting the yolks' heat tolerance.
The lecithin in yolks is a potent emulsifier — the same molecule responsible for the stability of mayonnaise and hollandaise. In a custard, it emulsifies the fat in the cream with the water phase, giving the finished custard its smooth, coating quality. A custard made with whole eggs (which have less lecithin per unit of thickening power) is cloudier and grainier. Yolk-only custards are the standard in French pastry precisely because of the lecithin contribution.
The ratio matters. Three yolks (about 60 g) to 200 g cream gives a pourable, coating custard — the base that, when baked in a bain-marie, becomes crème brûlée; when churned frozen, becomes ice cream; when poured over fruit, becomes sauce. Increase the yolks to 5 and reduce the cream slightly and you have a setting custard for tarts. Reduce the yolks and add milk instead of all cream and you have crème anglaise. The structure is the same; the ratios determine the application.
Common mistakes
Cooking over too high heat. A custard curdled on high heat is not recoverable. Use the lowest simmer your burner can maintain. If you have an induction hob, this is its ideal application.
Stopping too early. An under-cooked custard tastes eggy, raw, and thin. Wait for the coating (à la nappe) stage. Pull a spatula across the surface — if it leaves a clean track that holds, you're there.
Forgetting the ice bath. Carry-over cooking is significant in custard. The pan is hot, the custard is hot, and both will continue to cook the yolks. Straining into a cold bowl over an ice bath stops the cooking in seconds.
Skipping the strain. Every custard should be strained. Even a well-made custard accumulates chalazae (the white strands that connect the yolk to the white) and occasional small cooked bits. Straining gives the finished custard its clean, professional texture.
Over-ribboning. Whisking yolks and sugar for more than 2 minutes before heat is applied can start to denature the proteins prematurely and introduce too much air, causing the custard to foam rather than coat.
What to look for
- Ribboning stage: pale, thick, falls from the whisk in a slow ribbon. The sugar is dissolved; the yolks are slightly lightened.
- After tempering: warm, smooth, uniform. No yellow streaks, no white bits of cooked yolk.
- Early cooking: thin, liquid, just warm. You will doubt it is thickening — it isn't yet.
- À la nappe: coats the spatula. A finger-drawn line holds clean. This is the moment. Pull the pan off immediately.
Chef's view
This recipe is the chassis that sits under an entire section of the French pastry canon. Crème brûlée, crème caramel, ice cream base, crème Chiboust, tart filling, soufflé base — all of them start here. What changes is ratio, additions, and finishing technique. Custard base is not a recipe you make once; it is a skill you develop until you can execute it by feel.
The temperature range for a correctly cooked custard is uncomfortably narrow for a home kitchen without a thermometer. My recommendation: use one. An instant-read thermometer takes the anxiety out of the most critical moment and lets you focus on the texture cues rather than guessing. Target 78–82°C and pull the pan. At 78°C the custard is just barely coating; at 82°C it is richly coating and close to the edge. Above 85°C you are in trouble.
The vanilla pod is not optional for a custard intended for crème brûlée or ice cream — the flavor of real vanilla extract at this ratio is thinner than a pod. For pastry cream destined for a tart where other flavors are present, extract is acceptable.
Chef Test Notes
Tested at three end temperatures: 75°C (thin, slightly eggy), 80°C (coating, smooth, correct), and 85°C (grainy, beginning to curdle). The 80°C sample was the target and the one that set correctly when chilled. The 85°C sample was technically usable if strained aggressively but had a slightly grainy mouthfeel that a trained palate would notice.
Related glossary terms
- Liaison — the same egg-yolk-in-liquid thickening principle, applied in savory sauces
- Emulsion — the fat-in-water structure the lecithin in yolks creates
- Tempering — the gradual temperature-raising technique that prevents the yolks from scrambling
- Coagulation — the protein stiffening that thickens the custard at the right temperature