Why it works: Butter and bread are a kitchen classic. They rank in the top 7% of all ingredient pairs, and cooks put them together in 27,232 recipes. Both carry delta-decalactone, which smells sweet, creamy. The science ↓
Potatoes Au Gratin
Ingredients
Directions
The book says “a quick oven”. The 400°F (200°C) in the steps is the modern equivalent, not the book's own figure.
Make the white sauce
Make a white sauce by melting the butter, then whisking in the flour, salt, and white pepper.
Gradually add the milk, stirring until the sauce thickens.
Assemble and bake
Butter a baking dish and layer in some of the sauce, followed by a layer of potatoes seasoned with salt and pepper.
Repeat the layers until all ingredients are used.
Mix the melted butter with the bread crumbs and spread over the top.
Bake in a 400°F (200°C) oven for 20 minutes or until browned.
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.
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Butter + breadtop 7% of all pairsSmell alikemoderateCooked together27,232 recipes
Shared aroma: delta-decalactone (sweet, creamy).
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Butter + milktop 7% of all pairsSmell alikemoderateCooked together81,283 recipes
Shared aroma: (z)-4-heptenal (biscuit, cream).
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Milk + potatotop 9% of all pairsSmell alikemoderateCooked together3,611 recipes
Shared aroma: (e,z)-2,6-nonadienal (cucumber, melon).
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Milk + breadtop 11% of all pairsSmell alikemoderateCooked together11,466 recipes
Shared aroma: 2-undecenal (sweet).
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Butter + flourtop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
Butter and flour barely smell alike, yet cooks put them together in 124,287 recipes: they work on texture and structure more than aroma.
Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs
What each ingredient does
- Butter
- Melted butter in the sauce and crumb topping adds richness and helps the crumbs brown.
- Flour
- Cooked with butter, it thickens the milk into a smooth white sauce.
- Milk
- Forms the liquid base of the white sauce that coats the potatoes.
- Potatoes
- Form the bulk of the dish, absorbing the sauce as they bake.
- Bread crumbs
- Form a crisp, browned topping over the layers.
The step that matters
Gradually add the milk while stirring. Adding milk slowly while stirring lets the starch in the flour disperse and swell evenly, giving a smooth sauce instead of lumps.
Swap the white pepper
How well each one fits the dish's main ingredients (butter, flour, milk, potato, bread):
- Nutmegfits better
- Cinnamonfits better
- Parsleyfits better
- White pepperthe original
Fit is the average pairing score against butter, flour, milk, potato, bread. Candidates are from the same food group and used in at least 100 recipes.
“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.
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