Genoise Sponge

Before you start

Genoise gets its lift almost entirely from air whipped into warm whole eggs and sugar. There is no baking powder and very little fat, so the cake is light, springy and slightly dry on its own. That dryness is the point: a genoise is built to drink up a flavored syrup and hold layers of cream, fruit or buttercream without collapsing.

Three moments decide the result. Warm the eggs and sugar to about 43°C (110°F) so they whip to a stable, thick foam. Fold the flour in gently but completely, because pockets of flour bake into dense streaks. Then temper the melted butter into a scoop of batter before adding it back, since butter poured straight in sinks and deflates the foam.

Ingredients

• 4 large (about 200 g without shells) eggs — room temperature
• 125 g (½ cup + 2 tbsp) granulated sugar
• 125 g (1 cup + 2 tbsp) cake flour — sifted after weighing
• ⅛ tsp fine salt
• 30 g (2 tbsp) unsalted butter — melted and kept warm
• 1 tsp vanilla extract

Method

1. Heat the oven to 175°C (350°F) with a rack in the center. Line the bottom of the pan with a parchment circle. Lightly butter and flour the bottom only; leaving the sides bare gives the batter something to climb.
2. Sift the cake flour and salt together twice. Keep the melted butter and vanilla together in a small bowl somewhere warm.
3. Whisk the eggs and sugar in the mixer bowl set over a pan of barely simmering water. Keep whisking until the sugar dissolves and the mixture reaches 43°C (110°F), about 3 to 4 minutes. It should feel warm, not hot, on your finger.
4. Move the bowl to the mixer and whip on high speed for 6 to 8 minutes, until the foam has tripled, looks pale ivory and falls from the whisk in a thick ribbon that sits on the surface for a few seconds. Reduce to medium-low for 1 minute to even out the bubbles.
5. Sift one-third of the flour over the foam and fold it in with a spatula, cutting down through the middle and sweeping up the side while you turn the bowl. Repeat with the remaining flour in two additions, folding only until no dry pockets remain.
6. Stir about 1 cup of batter into the warm butter and vanilla until smooth. Fold this mixture back into the main batter in a few strokes.
7. Pour the batter into the pan and smooth the top. Bake for 25 to 30 minutes, until the top is golden, springs back when pressed lightly and the cake has just begun to pull away from the sides.
8. Cool in the pan on a rack for 10 minutes. Run a thin knife around the edge, turn the cake out, peel off the parchment and cool completely before slicing into layers.

Tips for success

• Weigh the eggs. A genoise depends on the ratio of egg to flour, and four eggs can vary by 30 grams or more.
• Do not open the oven in the first 20 minutes. A sudden draft can cause the foam to sink before the crumb sets.
• For a split cake, a serrated knife and a toothpick guide around the edge give three even 1.5 cm layers. Brush each layer with syrup before filling.

Substitutions

Cake flour

Use 105 g all-purpose flour plus 20 g cornstarch, sifted together three times. The crumb is slightly firmer but still tender.

Melted butter

A neutral oil works and stays softer when refrigerated, but you lose the buttery flavor. You can also leave the fat out for a drier, sturdier sponge for heavy soaking.

Vanilla extract

Replace with finely grated lemon or orange zest folded in with the last of the flour for a citrus sponge.

Variations

Chocolate genoise

Replace 25 g of the cake flour with 25 g Dutch-process cocoa, sifted together with the flour.

Brown butter genoise

Brown 40 g butter, strain out the solids if you like, and use 30 g of it warm in place of the plain melted butter.

Troubleshooting

Dense, rubbery band at the bottom

The butter or undissolved flour sank before the cake set. Temper the butter into some batter first and fold until the batter is uniform, scraping the bottom of the bowl.

Cake rose, then sank in the center

The foam was underwhipped or the cake came out early. Whip to a thick, lasting ribbon and bake until the center springs back, not just the edges.

Cake is flat and tight

The eggs were cold or the batter was overfolded. Warm the egg mixture to 43°C (110°F) and stop folding as soon as the flour disappears.

Storage

Wrap the cooled genoise tightly and keep it at room temperature for up to 2 days, or freeze it for up to 2 months. Thaw in the wrapping. Once it is soaked and filled with cream, refrigerate the assembled cake and eat it within 3 days.

Safety notes

Do not taste the raw batter; it contains raw egg and raw flour. Contains egg, wheat and milk.