Quick answer: one Bourbon vanilla bean, split and scraped, is enough for half a litre to a litre of milk. It infuses in the hot milk, covered and off the heat, with its caviar. Whisk the yolks with the sugar, pour in the milk, and cook over low heat until it coats the spoon, never letting it boil. For a strongly flavoured custard, where vanilla is the point of the dessert, our benchmarks run from 2 to 4 beans per litre: the low end of the range for a large bean, the high end for a small one.
Vanilla custard is the recipe that shows a vanilla for what it is: milk, egg yolks, sugar and a bean, nothing to dress it up. Our family grows and cures this vanilla in the SAVA region, in north-eastern Madagascar, and it is in a custard that we love to have people taste it, because everything reads there: the fruit, the woodiness, the roundness.
What you need, and in what proportions
For half a litre of whole milk, kitchens agree on wide ranges rather than gram-precise measures: 4 to 6 egg yolks, and 60 to 100 g of sugar depending on whether you want a serving custard, poured over a cake, or a sweeter one that will become an ice cream.
And the vanilla: one whole, supple bean, split from end to end, its caviar scraped out with the back of the knife. Bean and caviar go into the milk together. The emptied bean still carries plenty of aroma, never throw it away at this stage.
The classic method, step by step
1. Infuse the bean in the hot milk
Pour the milk into a saucepan, add the split bean and its caviar, and heat until it simmers, without boiling. Remove from the heat, cover, and let it infuse. A quarter of an hour already gives a frank custard; half an hour makes it deeper. The lid matters: vanilla's aromas leave with the steam of a milk left uncovered.
2. Whisk the yolks with the sugar
While it infuses, whisk the yolks with the sugar until the mixture pales and turns frothy. Do not do this too soon: sugar left in a heap on unwhisked yolks dries them out and forms grains that no longer dissolve.
3. Temper, then cook to the coating stage
Reheat the infused milk, bean included, then pour a small part of it over the yolks while whisking, to warm them without cooking them. Pour everything back into the saucepan. Cook over low heat, stirring constantly with a spatula, scraping the bottom and edges, until the custard thickens slightly and coats the spatula: run a finger across it, the line should stay clean. On a thermometer, the classic kitchen benchmark sits a little under 85°C, and in every case far from boiling.
4. Strain, or not
Remove the bean. You can pass the custard through a fine sieve to remove any strands of egg, but a fine sieve also holds back part of the caviar. We prefer to keep it in: those tiny black grains are the signature of a custard made with a real bean. If you do strain it, scrape the sieve to send the caviar back into the custard. Then chill it quickly, with cling film pressed to the surface.
What makes or breaks a vanilla custard
The coating stage
Everything happens in the last few seconds. The custard stays liquid for a long time, then thickens all at once. Lower the heat as soon as steam rises, do not leave the pan, and keep a cold bowl within reach to pour the custard into as soon as it coats: the pan retains enough heat to keep cooking off the stove.
Why it curdles
A vanilla custard curdles when the yolks cook too much: the egg proteins tighten, release liquid, and the custard turns grainy, with the look of curdled milk. The causes are always the same: too high a heat, a boil, or a spatula that stops and lets the egg catch on the bottom.
How to save it
If grains have just appeared, immediately pour the custard into a cold container and blend it for a few seconds with a stick blender: the texture turns smooth again in most cases. A custard that has properly boiled is lost for serving, but it still flavours a rice pudding.
Which bean grade to choose
Our beans are measured with a gauge and sorted into four grades: S from 10 to 12 cm, M from 13 to 15 cm, L from 16 to 18 cm and XL from 19 to 20 cm. It is the same Bourbon vanilla, Vanilla planifolia, from the same harvest. What changes is the matter: all else being equal, a 19 cm bean carries twice as many seeds as an 11 cm bean.
For vanilla custard, our Bourbon vanilla beans page says it plainly: grade M is the everyday baking grade, custards, flans, ice creams; grade L is for desserts where vanilla is the point and the caviar should be visible. A vanilla custard served on its own, in a glass or under a floating island, deserves an L.
The number follows the grade: with a large bean, stay at the low end of the range; with a small one, go higher. Our dosage table details these benchmarks, and our page on vanilla grades explains why only a Gourmet bean, supple and whole, splits cleanly under the knife.
Variations that start from the same base
- Vanilla ice cream: a richer custard, with a share of liquid cream and a little more sugar, chilled then churned. Cold mutes aromas, so aim for the top of the bean range.
- Floating island: the custard is served cold, under poached egg whites and a thread of caramel. It is the dessert's only flavoured element, and visible caviar is entirely at home in it.
- Crème brûlée: the same family, but with cream rather than milk, and baked in the oven. We give it a full page: Bourbon vanilla crème brûlée.
- Rice pudding and flan: vanilla plays a supporting role rather than dominating, so stay at the low end of the range.
One bean serves more than once
The bean removed from the custard has not given everything. Rinse it under clean water, pat it dry and let it air-dry. Slipped into a jar of sugar, it makes a homemade vanilla sugar within a few weeks. It can also infuse a second time, in a rice pudding or a syrup, by extending the contact time.
Beans waiting their turn keep in their resealed pouch or in an airtight glass tube, at room temperature and away from light, never in the fridge. Our full advice is in the page storing and preparing beans. And if a white veil appears on a well-stored bean, read our page on vanilla frost before throwing it away.
Frequently asked questions
Should you scrape the caviar, or infuse the whole bean?
Both, together. The caviar gives the black grains and part of the aroma; the bean's wall also carries a good deal of it. Our page on vanilla caviar shows the method.
Can you make a vanilla custard with extract or powder?
You can, but the result is not the same. Extract is added off the heat, at the end, because the alcohol that carries it evaporates during cooking. Powder gives the grains without the depth of a real infusion. For a vanilla custard, the split bean remains the safest route.
How long does a vanilla custard keep?
Two days in the fridge, with cling film pressed to the surface. Serve it very cold, or warm over a hot dessert, but never reheat it over high heat: it would curdle just as it would during cooking.
All these beans come from our family, in the SAVA, and are gathered in the Bourbon vanilla collection. The rest of our pages are kept in the Wiki.
