Basic Sponge Cake

• Prep30 min
• Cook30 min
• Total2 h 10 min
• Serves10

Ingredients

• 5 large eggs, at room temperature
• 150 g sugar (3/4 cup)
• 1 tsp vanilla extract
• 120 g all-purpose flour (1 cup)
• 30 g cornstarch (1/4 cup)
• 1/8 tsp salt
• Butter or baking spray and parchment paper, for the pan

Instructions

1. Heat the oven to 180°C (350°F). Grease only the bottom of a 23 cm (9 in) round pan or springform at least 7.5 cm (3 in) deep and line it with parchment. Leave the sides bare so the batter can grip them as it climbs. If your eggs are cold, set them in a bowl of warm tap water for 10 minutes: cold eggs whip slowly and never get as thick.
2. Place the flour, cornstarch and salt in the clean, dry mixing bowl and mix 5 sec/speed 6 to blend and aerate. Transfer to a fine sieve set over a bowl and wipe the mixing bowl dry.
3. Insert the butterfly whisk. Add the eggs, sugar and vanilla and whip 6 min/37°C (98°F)/speed 4. Warming the eggs to body temperature dissolves the sugar and relaxes the egg proteins, so they stretch around more air and make a stronger foam.
4. When it stops, whip 8 min/speed 4 without heat. As the foam cools it thickens, turns pale and grows to more than triple its volume. Lift some with the spatula: it should fall in a thick ribbon that sits on the surface for about 3 seconds before it sinks in. This is the ribbon stage. If it sinks right away, whip 2 min/speed 4 more.
5. Remove the butterfly whisk and pour the foam into a large, wide bowl. Sift a third of the flour mixture over it and fold it in by hand with a large spatula: cut down through the center, sweep along the bottom and up the side, and turn the bowl a quarter turn each time. Repeat with the rest of the flour in two more additions, just until no dry flour shows. Fold, never stir: stirring pops the bubbles, and the bubbles are the only thing that makes this cake rise.
6. Pour the batter into the pan and smooth the top gently. Bake in the oven 25 to 30 minutes, without opening the door for the first 20 minutes, until golden, the top springs back when you touch it and the edges start to pull away from the pan.
7. Cool 10 minutes in the pan. Run a thin knife around the edge, turn the cake out onto a rack, peel off the parchment and flip it right side up onto a second rack. Let it cool completely, about 1 hour, before slicing or filling.

Tips

• Soaking syrup (almíbar): a sponge is drier than a butter cake on purpose, so it drinks syrup well. Cook 100 g water and 100 g sugar 5 min/90°C (195°F)/speed 2, let it cool and add 1 tsp vanilla or a strip of orange peel. Brush it over the layers before you fill them.
• Chocolate sponge: replace 30 g (1/4 cup) of the flour with unsweetened cocoa powder and mix it with the flour in step 2. Cocoa is heavier than flour, so fold with extra care.
• Lemon sponge: before step 3, place the sugar and the peel of 2 lemons (only the yellow part, in strips) in the dry mixing bowl and mill 10 sec/speed 10. Scrape down the sides, then insert the butterfly whisk and continue with the eggs and vanilla.
• To split it into layers, let the cake cool completely, or chill it 1 hour, wrapped. Mark the middle with toothpicks all around and saw gently with a long serrated knife, turning the cake as you go. Wrapped well, it keeps 2 days at room temperature or 2 months in the freezer.