As a chef who’s slightly obsessed with texture, I have to say this fluffy Castella sponge cake is the definition of soft perfection. Each slice has that signature bounce, an ultra smooth crumb, and a light sweetness that melts on the tongue. I make this when I want a cake that feels elegant yet humble, with no need for frosting or fillings just pure, pillowy satisfaction.
Why You’ll Fall in Love With This Castella Sponge
Originating from Japan and inspired by European sponge cakes, Castella (or kasutera) has a uniquely moist, fluffy texture that makes it stand apart from other sponges. The secret? It’s all in the meringue, water bath baking, and gentle folding and when done right, the result is unbeatable.
- Feather light texture: Thanks to whipped egg whites and steam baking, every bite feels like air.
- No butter or heavy fats: It’s made with oil and milk for softness without richness overload.
- Subtly sweet flavor: Just enough sugar to feel indulgent, but never overwhelming.
- Beautiful golden crust: The top bakes into a lightly caramelized layer, no extra topping needed.
- Elegant enough for any table: From afternoon tea to light dessert, it’s always the right choice.
Step by Step Guide to a Perfect Fluffy Castella Cake
This cake may look delicate, but it’s very doable with a little care. Follow these steps exactly and you’ll get a perfectly risen, smooth topped sponge with no cracks or collapse.
Ingredients
- 6 egg whites
- 6 egg yolks
- 85 g sugar (superfine or caster is ideal)
- 80 ml vegetable oil
- 90 g cake flour or sponge flour
- 70 ml milk
- ¼ tsp salt
Instructions
1: Whip the Meringue
- In a clean, dry bowl, beat the egg whites until they become foamy.
- Gradually add sugar and continue whipping until stiff peaks form the meringue should be glossy and stable.
2: Prepare the Batter Base
- Heat the oil for 90 seconds in the microwave or gently on the stove. It should be warm but not boiling.
- Add sifted flour and salt into the warm oil and mix until smooth.
- Stir in the egg yolks and milk, mixing until you have a silky, lump free batter.
3: Fold in the Meringue
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- Take one third of the meringue and gently mix it into the batter to loosen it.
- Then, fold in the remaining meringue in two more additions, using a spatula and gentle motions to keep the batter airy.
4: Pour and Tap
- Pour the batter into a parchment lined square or loaf tin (avoid greasing the sides).
- Tap the tin on the counter several times to remove air bubbles that might cause holes during baking.
5: Water Bath Baking
- Place the cake tin inside a larger baking dish and fill the outer dish with hot water halfway up the sides.
- Bake in a preheated oven at 150°C (300°F) for about 60 minutes, or until the center springs back and a toothpick comes out clean.
6: Cool and Slice
- When done, gently bang the tin on the counter a few times to release steam and prevent shrinking.
- Let the cake cool completely in the tin, then transfer to a cutting board and slice with a serrated knife.
Pro Tips for Castella Success
Techniques That Make a Difference
This isn’t your average sponge cake the method is part of what gives Castella its signature bounce and cotton soft bite. Here are tips I follow every time:
- Use room temperature eggs: They whip better and give more volume.
- Don’t overheat the oil: Just warm enough to blend the flour, but not hot enough to scramble the yolks.
- Always sift your flour: Even a few lumps can weigh the cake down or cause streaks.
- Fold, don’t stir: Keep your motions slow and careful to avoid deflating the airy meringue.
- Bake low and slow: High heat causes cracking 150°C and steam creates that smooth, glossy top.
Creative Castella Cake Twists
This cake is stunning in its simplicity, but here’s how I love to experiment with flavors without compromising texture:
- Matcha Castella: Add 1 teaspoon of sifted matcha powder with the flour for a subtle earthy twist.
- Honey infused: Swap out 1 tablespoon of sugar for honey for a deeper golden crust and natural sweetness.
- Lemon version: Add 1 teaspoon of lemon zest and a tiny splash of lemon juice for a bright finish.
- Layered with jam: Slice the cake horizontally and add a thin spread of fruit jam or citrus marmalade between layers.
- Mini Castella bites: Bake the batter in cupcake molds using the same water bath method for adorable, single serve treats.
Perfect Pairings and Serving Suggestions
What to Serve With Fluffy Castella Sponge Cake
This sponge cake shines on its own, but pairing it with the right drink or side can turn it into a complete experience. Light, not overly sweet, and full of bounce, Castella complements a range of beverages and toppings.
| Pairing | Flavor Profile | Why It Works |
|---|---|---|
| Matcha Latte | Earthy and creamy | Balances the soft sweetness with rich, roasted green tea |
| Black Coffee | Bold and bitter | Highlights the subtle sweetness of the sponge cake |
| Whipped Cream and Berries | Light, sweet, and tart | Adds color and flavor contrast without overwhelming the cake |
| Milk Tea | Silky and slightly floral | A popular Asian pairing that enhances the cake’s milky notes |
| Fresh Fruit Compote | Sweet and syrupy | Moistens the crumb while adding visual flair |
Storage, Make Ahead, and Batch Baking Tips
How to Store Castella Cake Properly
The beauty of a good Castella sponge cake is that it actually improves in texture after resting. The cake becomes slightly denser and even more moist the day after baking making it perfect for advance preparation.
- Room Temperature: Wrap the cooled cake tightly in parchment paper and plastic wrap. Store in an airtight container at room temperature for up to 3 days.
- Refrigeration: For longer storage, refrigerate wrapped cake for up to 5 days. Bring to room temperature before serving to regain its soft texture.
- Freezing: Slice the cake, wrap each piece in parchment and then plastic wrap. Freeze in a zip top bag for up to 1 month. Thaw slices at room temp before serving.
Frequently Asked Questions About Castella Sponge Cake
Why is my Castella sponge not fluffy?
This usually happens if the meringue was over or under whipped, or if you folded too aggressively and lost air. Gently folding in stiff, glossy peaks is the key.
Can I use all purpose flour instead of cake flour?
Yes, but the texture will be slightly denser. For better results, substitute with a DIY cake flour (remove 2 tablespoons of flour per cup and replace with cornstarch).
What pan works best for Castella?
A square or rectangular nonstick pan lined with parchment is ideal. Avoid springform pans, as water baths can leak.
Can I skip the water bath?
Not recommended. The steam helps prevent cracking, keeps the top glossy, and ensures even, gentle baking.
How do I store Castella sponge cake?
Wrap in plastic wrap and store at room temperature for up to 3 days. For longer storage, refrigerate for up to 5 days or freeze for 1 month.
What’s the best knife for cutting Castella?
Use a sharp serrated knife and wipe clean between slices to keep the edges smooth and prevent crumbling.
Why did my cake collapse after baking?
This can happen if the cake is underbaked or if it’s cooled too quickly. Always do the toothpick test and let it cool slowly in the pan before unmolding.
Is Castella cake gluten free?
Not as written, but you can try a gluten free cake flour blend. Results may vary, so test in small batches first.
Can I make mini Castella cakes?
Absolutely! Use muffin molds or mini loaf pans and reduce baking time to 20-25 minutes. Still use the water bath method for best texture.
Can I make this dairy free?
Yes, substitute the milk with unsweetened almond or soy milk. Texture remains similar, but flavor will change slightly.
