Fluffy Castella (Kasutera) Cake Recipe:The Light and Airy Japanese Sponge Cake

Castella Cake is a light, fluffy Japanese sponge cake that’s all about texture and subtle sweetness. Made with simple pantry ingredients like eggs, flour, and sugar, this airy treat is perfect for afternoon tea, elegant brunches, or whenever you're craving something soft and satisfying. If you love desserts that melt in your mouth without being overly sweet, this one’s for you.

What Is Castella Cake?

Originally from Portugal, Castella Cake (or Kasutera) found a new identity in Japan centuries ago. It’s now a beloved staple in Japanese bakeries—recognized for its fine, moist crumb and springy texture. Unlike traditional sponge cakes, Castella has a denser bounce due to its unique mixing method, yet it remains incredibly soft and light. Often baked in a rectangular mold and sliced into neat blocks, it’s a popular choice for tea time and gifting.

Why Everyone Will Love This Recipe

• Feather-light texture: Thanks to whipped egg whites, each bite feels like a cloud.
• Naturally sweet: Made without butter or heavy cream—just a touch of sugar and vanilla.
• Perfect for any occasion: Elegant enough for entertaining, simple enough for everyday.
• Customizable: Serve with fruit, whipped cream, or enjoy it plain with a dusting of powdered sugar.
• No fancy equipment required: All you need is a whisk and a basic square cake pan.

Pro Tips for the Best Castella Cake

• Use room temperature eggs for the best volume when whipping.
• Whisk egg yolks and sugar until pale and thick—this helps create that signature fluffy rise.
• Don’t skip the sifting: It aerates the flour and prevents clumps.
• Fold gently when incorporating egg whites to avoid deflating the batter.
• Bake low and slow: 160°C (320°F) ensures even cooking and a golden finish.
• Optional flavors: A touch of lemon zest adds brightness; vanilla seeds offer deep aroma.

Frequently Asked Questions

Can I Use Cake Flour Instead of All-Purpose Flour?

Yes, cake flour can make the cake even lighter, but all-purpose works perfectly and gives slightly more structure.

Why Did My Cake Collapse After Baking?

This usually happens if the egg whites were over- or under-whipped, or if the cake was underbaked. Be sure to bake for the full hour and check doneness with a toothpick.

Can I Make Castella Cake Without Vanilla Bean?

Absolutely. You can substitute 1 teaspoon of vanilla extract if you don't have a vanilla bean.

What Size Pan Should I Use?

A square 20 x 20 cm (about 8 x 8 inch) pan works best. Using a different size will affect the height and bake time.

Can I Fill Castella Cake With Cream or Fruit?

Yes! While traditionally served plain, it’s delicious with whipped cream and fresh berries layered in.

How to Store

Let the cake cool completely, then wrap it tightly in plastic wrap or store in an airtight container. It will stay fresh at room temperature for up to 2 days, or in the refrigerator for 4 days. To enjoy it warm, reheat slices gently in the microwave for 10–15 seconds.

How to Freeze

Wrap individual slices or the whole cake tightly in plastic wrap, then place in a freezer bag or container. It freezes well for up to 2 months. To serve, thaw at room temperature for 1–2 hours, or microwave in short bursts until soft.

How To Make Castella Cake

Step 1

Step 1

Preheat your oven to 320°F (160°C). Line a 20 x 20 cm square cake pan with parchment paper. Separate the eggs, placing whites and yolks in separate large bowls. Whisk the yolks with half the sugar, vanilla seeds, and lemon zest (if using) until light and fluffy.

Preheat your oven to 320°F (160°C). Line a 20 x 20 cm square cake pan with parchment paper. Separate the eggs, placing whites and yolks in separate large bowls. Whisk the yolks with half the sugar, vanilla seeds, and lemon zest (if using) until light and fluffy.

Gradually add oil, whisking continuously, then add milk and mix until smooth. Sift in the flour and fold it in gently until fully incorporated. In a clean bowl, beat the egg whites until foamy. Gradually add the remaining sugar and whip until stiff peaks form. Fold the egg whites into the yolk mixture in batches, using soft, upward motions to keep the batter airy.

Step 2

Step 2

Gradually add oil, whisking continuously, then add milk and mix until smooth. Sift in the flour and fold it in gently until fully incorporated. In a clean bowl, beat the egg whites until foamy. Gradually add the remaining sugar and whip until stiff peaks form. Fold the egg whites into the yolk mixture in batches, using soft, upward motions to keep the batter airy.

Pour into the prepared pan, smoothing the top with a spatula. Bake for 1 hour, or until golden and a toothpick inserted in the center comes out clean.

Step 3

Step 3

Pour into the prepared pan, smoothing the top with a spatula. Bake for 1 hour, or until golden and a toothpick inserted in the center comes out clean.

Let it cool slightly before removing from the pan. Dust with powdered sugar and slice to serve.