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 egg yolks with the castor sugar.
Gradually add the Vienna flour and baking powder.
Gently fold in the whipped egg whites until combined.
Bake
Butter a plain mold and pour in the mixture.
Bake for 30 minutes until done.
Ice and serve
Let it cool, then cover with icing made by beating butter and icing sugar together with essence of coffee.
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 trap air for lift, while yolks add richness and structure.
- Vienna flour
- Provides the starch and gluten that set the cake's structure as it bakes.
- Baking powder
- Releases gas during baking so the cake rises and becomes light.
- Castor sugar
- Sweetens the batter and helps stabilise the beaten egg yolks.
- Butter
- Adds fat for a rich flavour and a smooth, spreadable icing.
- Icing sugar
- Sweetens the icing and gives it a fine, smooth texture when beaten with butter.
The step that matters
Fold in the whipped egg whites gently. The cake's rise depends on air held in the whites. Vigorous stirring deflates the foam, so the cake can bake flat and dense.
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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