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 quick 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 Vienna flour, potato flour, and baking powder, mixing until smooth.
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.
Turn the cake out and let it cool completely.
Make the icing
To make the icing, beat the butter and icing sugar together until smooth.
Add the essence of coffee drop by drop to the icing.
Finish
Once the cake is iced, store it in a cool place until ready to serve.
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.
-
Flour + buttertop 12% of all pairsSmell alikelowCooked together124,287 recipes
Shared aroma: isobutyraldehyde (malty, green).
-
Potato + coffeetop 12% of all pairsSmell alikemoderateCooked together167 recipes
Shared aroma: sotolon (curry, maple).
-
Potato + buttertop 13% of all pairsSmell alikemoderateCooked together6,456 recipes
Shared aroma: (z)-4-heptenal (biscuit, cream).
-
Sugar + flourtop 15% of all pairsSmell alikemoderateCooked together92,116 recipes
Shared aroma: phenylacetaldehyde (hawthorne, honey).
-
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.
- Castor sugar
- Sweetens the batter and helps create a fine, tender crumb.
- Vienna flour
- Provides the main structure that holds the cake together.
- Baking powder
- Releases gas in the batter, helping the cake rise.
- Fresh butter
- Adds fat for moisture, tenderness, and a rich icing.
- Essence of coffee
- Adds concentrated coffee flavour to the icing.
The step that matters
Fold in the whipped egg whites gently. Whipped whites hold air that makes the cake light. Stirring vigorously deflates them, so the cake rises less and turns 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.
You might also like
Deep-Fried Potato Balls119 recipes
Coffee Ice Cream91 recipes
Orange Potato Bread80 recipes
Coffee Custard27 recipesThe free Flavor Lab newsletter: one surprising pairing a week and the molecular reason it works, in 60 seconds. No spam, unsubscribe anytime.
Prefer an account? Create a free account to save pairings and unlock the full chemistry.