Why it works: Milk and butter are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 81,283 recipes. Both carry (z)-4-heptenal, which smells biscuit, cream. The science ↓
French Custards
Ingredients
Directions
Make the custard
Gently boil the milk with sugar and a pinch of salt for a few minutes.
Remove from heat and briskly stir in the egg yolks.
Butter a round deep dish and pour in the custard mixture.
Bake and serve
Place the dish in a pan of boiling water, ensuring the water does not touch the custard.
Let it simmer gently for 1 to 1.5 hours until firm in the middle.
Keep a few live embers on the lid to prevent steam from falling into the custard.
Serve the custard cold, garnished with chopped macaroons or ratafias around the edge.
Transcribed from a scanned cookbook and modernised for today's kitchens. Where the book gave no heat or time, or said "a moderate oven", the temperatures and times here may be modern equivalents rather than the book's own figures.
Photo for illustrative purposes only · Contact us to use it
Explore the science
The flavor team
The pairs that carry this dish. Each one is judged two ways: how much their aromas overlap, and how often cooks already put them together.
-
Milk + buttertop 7% of all pairsSmell alikemoderateCooked together81,283 recipes
Shared aroma: (z)-4-heptenal (biscuit, cream).
-
Cream + buttertop 8% of all pairsSmell alikemoderateCooked together41,516 recipes
Shared aroma: delta-dodecalactone (sweet, creamy).
-
Cream + sugartop 9% of all pairsSmell alikemoderateCooked together43,450 recipes
Shared aroma: 2,3-butanedione (butter, sweet).
-
Egg + buttertop 17% of all pairsSmell alikemoderateCooked together118,967 recipes
Shared aroma: decanal (soap, orange peel).
-
Sugar + buttertop 17% of all pairsSmell alikemoderateCooked together98,233 recipes
Shared aroma: guaiacol (smoky, sweet).
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Egg yolks
- Set the custard as they cook, giving it a firm, sliceable structure.
- Milk
- Forms the liquid base and provides moisture for a smooth, tender custard.
- Sugar
- Adds sweetness and balances the richness of the yolks and milk.
The step that matters
Keep the water bath from touching the custard and simmer gently. Egg proteins set at moderate heat; if the custard is exposed to boiling water or steam drops onto it, it can curdle or become grainy and pitted instead of smooth and firm.
“What each ingredient does” and “The step that matters” were written by Claude from this recipe’s own method and reviewed in samples by CompKitchen.
More french custard recipes
You might also like
The free Flavor Lab newsletter: one surprising pairing a week and the molecular reason it works, in 60 seconds. No spam, unsubscribe anytime.
Prefer an account? Create a free account to save pairings and unlock the full chemistry.

White Cake431 recipes
Pound Cake373 recipes
Orange Bundt Cake349 recipes
Spice Cake344 recipes