Why it works: Flour and butter are a kitchen classic. They rank in the top 12% of all ingredient pairs, and cooks put them together in 124,287 recipes. Both carry isobutyraldehyde, which smells malty, green. The science ↓
Mocha Cake
Ingredients
Directions
The book says “a moderate oven”. The 400°F (200°C) in the steps is the modern equivalent, not the book's own figure.
Make the batter
Preheat the oven to 400°F (200°C).
Beat the yolks of the eggs with the castor sugar.
Gradually add the flour and baking powder.
Gently fold in the whipped egg whites until combined.
Butter a plain mold and pour in the mixture.
Bake and cool
Bake for 30 minutes or until done.
Let the cake cool completely before icing.
Ice and finish
To make the icing, beat the butter and icing sugar until smooth.
Add the coffee essence drop by drop.
Ice the cooled cake and decorate as desired.
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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Flour + buttertop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
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Potato + coffeetop 12% of all pairsSmell alikemoderateCooked together167 recipes
Shared aroma: sotolon (curry, maple).
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Potato + buttertop 13% of all pairsSmell alikemoderateCooked together6,456 recipes
Shared aroma: (z)-4-heptenal (biscuit, cream).
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Sugar + flourtop 15% of all pairsSmell alikemoderateCooked together92,116 recipes
Shared aroma: phenylacetaldehyde (hawthorne, honey).
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Flour + potatotop 15% of all pairsSmell alikemoderateCooked together5,355 recipes
Shared aroma: isobutyraldehyde (malty, green).
Flour and butter 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
- Eggs
- Whipped whites give lift and structure, while the yolks add richness and moisture.
- Castor sugar
- Sweetens the batter and helps create a fine, tender crumb.
- Vienna flour
- Provides the flour structure that holds the cake's crumb together as it bakes.
- Baking powder
- Releases gas in the oven, helping the cake rise.
- Butter
- Adds fat for a smooth, rich icing with a soft mouthfeel.
- Coffee essence
- Gives the cake and icing its coffee flavour and aroma.
The step that matters
Gently fold in the whipped egg whites. Whipped egg whites hold air that makes the cake light. Stirring vigorously knocks this air out, so the cake bakes up dense instead of airy.
Swap the potato
How well each one fits the dish's main ingredients (egg, sugar, flour, butter, coffee):
- Arrowrootfits about as well
- Sweet potatofits about as well
- Asparagusfits about as well
- Potatothe original
Fit is the average pairing score against egg, sugar, flour, butter, coffee. 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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