Why it works: Butter and cream are a kitchen classic. They rank in the top 8% of all ingredient pairs, and cooks put them together in 41,516 recipes. Both carry delta-dodecalactone, which smells sweet, creamy. The science ↓
Onion Tart
Ingredients
Directions
The book says “a moderate oven”. The 350°F (175°C) in the steps is the modern equivalent, not the book's own figure.
Prepare the filling
Slice the onions.
Stew the sliced onions with 1 oz of butter without browning until tender.
Let the onions cool.
Mix the cooled onions with beaten eggs and cream.
Season the mixture with pepper and salt.
Make the crust
Make a dough with wheatmeal and the remaining butter, reserving a small amount.
Line a baking tin with the dough.
Assemble and bake
Pour the onion mixture into the lined tin.
Cut the reserved dough into thin strips.
Lay the strips crosswise over the tart to form diamond shapes.
Bake in a moderate oven at 350°F (175°C) until golden brown.
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.
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 + creamtop 8% of all pairsSmell alikemoderateCooked together41,516 recipes
Shared aroma: delta-dodecalactone (sweet, creamy).
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Onion + peppertop 11% of all pairsSmell alikemoderateCooked together68,474 recipes
Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).
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Onion + buttertop 15% of all pairsSmell alikemoderateCooked together42,912 recipes
Shared aroma: decanal (soap, orange peel).
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Butter + eggtop 17% of all pairsSmell alikemoderateCooked together118,967 recipes
Shared aroma: decanal (soap, orange peel).
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Onion + creamtop 18% of all pairsSmell alikelowCooked together10,827 recipes
Shared aroma: 2-nonanone (fruity, floral).
Onion and cream barely smell alike, yet cooks put them together in 10,827 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
- Spanish onions and english onions
- Form the main filling, turning sweet and soft when stewed.
- Eggs
- Bind the onion and cream mixture so it sets firm when baked.
- Cream
- Adds richness and moisture, helping the custard-like filling stay tender.
- Butter
- Enriches the dough and gives it a tender, short texture.
- Fine wheatmeal
- Forms the dough that holds the filling and browns in the oven.
The step that matters
Stew the onions without browning. Cooking the onions gently until tender, without browning, keeps their flavour mild and sweet. Browned onions turn bitter and darken the filling, and any moisture left in them can make the set custard watery.
Swap the onion
How well each one fits the dish's main ingredients (butter, egg, cream, pepper):
- Potatofits better
- Spinachfits better
- Asparagusfits better
- Onionthe original
Fit is the average pairing score against butter, egg, cream, pepper. 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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