KO EN Italian Dessert⏱ 55 minEdit history

Genoise (Whole-Egg Sponge)

Name: Genoise (Whole-Egg Sponge)
Prep time: 30 min
Cook time: 25 min
Total time: 55 min
Yield: 8 servings
Cuisine: Italian
Ingredients: 4 eggs; 120 g caster sugar; 110 g plain cake flour; 10 g potato starch; 1 pinch salt; 1 tsp vanilla extract; 40 g butter; 50 g caster sugar; 50 ml water; 1 tbsp rum or kirsch

A sponge cake with no raising agent at all, aerated by whipping whole eggs. Every other cake on this site either whips whites alone or creams solid butter; a whole egg is about a third yolk by weight, and the fat in that yolk gets into the bubble walls and breaks them, so cold whole egg barely foams. That is why the eggs and sugar are warmed to 40-45°C over a water bath before whipping. One page here performs that step as a procedure; the reason is in the cooking-eggs guide.

Steps

Heat the oven to 175°C and line the tin. Sift the flour, starch and salt twice — this flour goes into a foam and you cannot stir lumps out of it later.
⏲ 5 min
Put the eggs and sugar in a bowl over a water bath and whisk until they reach 40-45°C: the sugar completely dissolved, and just warm to a finger. This step is the whole cake. The fat in the yolk gets into the bubble walls and bursts them; warmed, that fat is fully liquid and the proteins unfold faster, so a foam forms at all.
⏲ 8 min
Off the heat, whip on high for 8-10 minutes. The volume roughly triples, and it is ready when a drizzle from the whisk holds its trace for about three seconds — the ribbon stage. Judge it by the trace, not the clock.
⏲ 10 min
Fold in the sifted flour in three goes, cutting through with a spatula. Do not stir: kill the foam and this cake has nothing left to rise on.
⏲ 5 min
Take a ladle of the batter, mix the warm melted butter into that first, and fold the mixture back in. Butter is fat too — the same fat the warming existed to overcome — so poured straight onto a finished foam it sinks the batter where it lands. Cold, it sets in streaks; hot, it melts the foam.
⏲ 4 min
Pour into the tin, level the surface and bake 25 minutes. Do not open the door for the first 15 (what your oven is doing).
⏲ 25 min
Turn it out of the tin at once and cool it upside down on a rack until completely cold. It shrinks a little; that is normal. For the syrup, boil the sugar and water, cool, stir in the spirit, and brush each cut face.
⏲ 10 min

Tips & Variations

Variations

Pan di Spagna: the Italian name for the same cake, and it usually has no butter at all. That makes it drier and more absorbent, which for a sponge meant to be soaked is an improvement.
Cocoa genoise: swap 20g of the flour for cocoa powder. Cocoa brings fat with it as well as starch, so do not go further than that.
How it differs from a French biscuit*: a biscuit whips the whites separately and folds them in. A genoise whips the eggs whole. That is exactly where the two part company on identical ingredients, and it is the easiest way to see what this page is about.
Where it gets used: it is the sponge in prinsesstårta, and layer cakes generally are built on this batter. Sachertorte and tiramisu use different sponges but share the habit of being soaked.
The name: from Genoa. ko.wikipedia files it as an Italian sponge cake named after the city and since absorbed into French pastry, which is the order things happened in.

Tips

The warming is the trick, and the reason is in cooking eggs. The first step of prinsesstårta reads "warm the eggs and sugar over a water bath to 40°C, then whip on high for 8 minutes" — the procedure only — and its tips then group that with Dobos torte and pound cake as "the same principle." It is not the same principle: Dobos folds a whites-only meringue, a pound cake creams solid butter, and whole egg is a third method. The warming step exists precisely because of that difference.
Four ways this site puts air into a cake batter. Pound cake creams butter, Dobos torte folds a meringue, chiffon cake folds a meringue and adds oil, and a genoise whips whole eggs.
A whole-egg foam is weaker than a meringue and steadier in exchange. The crumb comes out fine, close and springy rather than fluffy — and the price of not being fluffy is that it survives being split into layers and brushed with syrup. That is why this is the cake used as a layer sheet.
It is deliberately a dry cake. No milk, and no fat beyond 40g of butter, so on its own it is plain. As umm ali puts it, only something already dry takes up liquid and still holds its structure — so the soaking syrup is part of the design, not a cover for a fault.
Line the tin. Chiffon cake is baked in a tin with nothing on it at all, because that batter has to climb the walls. A genoise wants the opposite: all its air is already in the batter, so it needs nothing to grip and should release cleanly.
The ribbon stage is a look, not a time. Eight minutes is a guide; whether a drizzle holds its trace for three seconds is the test — the same discipline cooking eggs applies elsewhere.
Sift the flour twice. A lump inside a foam cannot be stirred out, and stirring is what destroys the foam. The answer is not to create the choice in the first place.