Light, airy, and delicately sweet, Castella sponge cake is a beloved Japanese treat known for its soft, bouncy texture and golden-brown crust. Perfect with a cup of tea or coffee, this cake is made with simple ingredients but requires a gentle touch for the perfect rise. Follow this detailed recipe to create a cloud-like Castella right in your own kitchen.
Ingredients:
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6 large egg whites
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6 large egg yolks
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85 grams granulated sugar
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80 ml vegetable oil (neutral flavor like canola or sunflower)
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90 grams cake flour or sponge flour (sifted)
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70 ml whole milk (room temperature)
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1/4 teaspoon salt
Step-by-Step Instructions:
1. Prepare the oven and pan:
Preheat your oven to 150°C (300°F). Line the bottom and sides of a square or rectangular cake pan with parchment paper. If using a springform pan or one prone to leaking, wrap the outside with foil to prevent water from the water bath seeping in.
2. Separate the eggs:
Carefully separate the egg whites from the yolks, making sure no yolk gets into the whites. Place the egg whites in a large, clean mixing bowl, and set them aside (preferably in the fridge) while you prepare the yolk mixture.
3. Make the yolk base:
In a separate bowl, whisk the egg yolks until smooth and slightly pale. Slowly add the vegetable oil, mixing until fully incorporated. Then pour in the milk and add the salt, continuing to whisk until the mixture is even and slightly thickened.
4. Add the flour:
Sift the cake flour directly into the yolk mixture. Using a spatula or whisk, fold gently until no lumps remain. The batter should be smooth but not over-mixed.
5. Beat the egg whites (meringue):
Take the chilled egg whites and beat them with an electric mixer on medium speed until they become foamy. Gradually add the sugar, a tablespoon at a time, and increase the speed to high. Beat until stiff, glossy peaks form. This is crucial for achieving the cake’s signature fluffiness.
6. Combine the mixtures:
Start by folding a third of the meringue into the yolk batter to lighten it. Use a spatula and fold gently in a circular motion, being careful not to deflate the air from the meringue. Add the remaining egg whites in two more batches, folding carefully each time until fully combined. The final batter should be airy and uniform.
7. Bake in a water bath:
Pour the batter into your prepared pan and gently tap it on the counter to release any large air bubbles. Place the pan into a larger baking tray and fill the outer tray with hot water until it reaches halfway up the sides of the cake pan. This steam bath helps keep the cake moist and prevents cracking.
8. Bake:
Bake for 60–70 minutes, or until the top is golden brown and a skewer inserted into the center comes out clean. Keep an eye on the cake in the last 10 minutes to avoid overbaking.
9. Cool and serve:
Once baked, remove the cake from the oven and let it sit in the pan for about 10 minutes. Then carefully remove it and let it cool completely on a wire rack. For best texture and flavor, wrap the cooled cake in plastic wrap and refrigerate it for a few hours or overnight before slicing.
Tips for Success:
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Room temperature ingredients help the batter mix more evenly. Let eggs and milk sit out for 20–30 minutes before starting.
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Don’t skip the sifting! Sifting the flour ensures a smooth batter and avoids clumps.
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Be gentle when folding the meringue. The air trapped in the egg whites is what gives this cake its incredible lightness.
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If you don’t have cake flour, you can make your own by replacing 2 tablespoons of every cup of all-purpose flour with cornstarch.
Serving Suggestions:
Slice the cake with a sharp knife dipped in warm water for neat edges. Serve it as-is, or top with whipped cream, a dusting of powdered sugar, or fresh berries for a more decadent dessert. It’s also delicious with a drizzle of honey or a dollop of sweet red bean paste.
