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Onion Soup

A creamy soup made with butter, onions, milk, bread, heavy cream, salt, and pepper.

From an old cookbook · modernised transcription
From a historical cookbook (Internet Archive) · 7 ingredients
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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 ↓

Onion Soup

Ingredients

Directions

Make the onions

  1. In a saucepan, melt the butter over medium heat until lightly browned.

  2. Slice the onions and add them to the saucepan; cook until they are soft and browned, but not burnt.

  3. Heat the milk in a separate pot until it reaches boiling point.

Assemble and serve

  1. In a tureen, place the broken bread at the bottom.

  2. Layer the cooked onions on top of the bread.

  3. Pour the hot milk over the onions.

  4. Add the heavy cream, and season with salt and pepper to taste.

Recipe from a historical cookbook (Internet Archive).

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.

  1. Butter + breadtop 7% of all pairs
    Smell alikemoderate
    Cooked together27,232 recipes

    Shared aroma: delta-decalactone (sweet, creamy).

  2. Butter + milktop 7% of all pairs
    Smell alikemoderate
    Cooked together81,283 recipes

    Shared aroma: (z)-4-heptenal (biscuit, cream).

  3. Butter + creamtop 8% of all pairs
    Smell alikemoderate
    Cooked together41,516 recipes

    Shared aroma: delta-dodecalactone (sweet, creamy).

  4. Milk + breadtop 11% of all pairs
    Smell alikemoderate
    Cooked together11,466 recipes

    Shared aroma: 2-undecenal (sweet).

  5. Onion + peppertop 11% of all pairs
    Smell alikemoderate
    Cooked together68,474 recipes

    Shared aroma: 2-isopropyl-3-methoxypyrazine (earthy, pea).

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Onions
Cooked slowly until soft and browned, they give the soup its sweet, savoury flavour.
Bread
Soaks up the hot milk and onions, giving the soup body and a soft, thick texture.
Milk
Forms the liquid base that softens the bread and carries the onion flavour.
Heavy cream
Adds richness and fat, producing a smoother, creamier mouthfeel.
Butter
Fat for browning the onions, adding nutty, rich flavour.

The step that matters

Cook the onions until soft and browned, not burnt. Slow cooking converts the onions' natural sugars into browned, caramelised flavour. If the heat is too high, the sugars scorch, leaving bitter notes that the milk and cream cannot mask.

Swap the onion

How well each one fits the dish's main ingredients (butter, milk, bread, cream, pepper):

  1. Potatofits better
  2. Capsicumfits better
  3. Asparagusfits about as well
  4. Onionthe original

Fit is the average pairing score against butter, milk, bread, 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.

More onion soup recipes

French 31Brown 15with Milk 7White 5Bavarian 4Bermuda 4 See all 236 →

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