Okay, let’s be real—there are cakes you bake, and then there’s the fluffy Castella sponge cake, which is on a whole other level of light and bouncy. This isn’t your typical butter cake. Nope. This baby is airy, cloud-like, and so soft that cutting into it almost feels wrong (but in the best way).
The first time I made this, I was convinced it was going to deflate on me—like, one wrong move and poof, pancake city. But once you get the hang of the meringue and that gentle folding, you’ll see how forgiving and fun it actually is. Plus, the water bath trick? Game-changer.
What Makes Castella Cake Special?
Castella has roots in Japan, though it originally came from Portuguese traders. Over time, it became a Japanese bakery favorite because of its signature fluffy texture and mild sweetness. Unlike frosted cakes, Castella is all about simplicity—you don’t need cream, frosting, or fillings. The cake itself is the star.
Think of it as the ultimate “snack cake” you can have with coffee, tea, or, let’s be honest, just standing over the counter with a fork.
Ingredients You’ll Need
Here’s the exact lineup to make one gorgeous loaf of fluffy Castella sponge cake:
- 6 egg whites
- 6 egg yolks
- 85 g sugar (superfine or caster works best)
- 80 ml vegetable oil
- 90 g cake flour or sponge flour
- 70 ml milk
- ¼ tsp salt
Pretty simple, right? Pantry basics, no fancy extras.
Step-by-Step Recipe
This method might look a little different than your everyday cakes, but trust me, each step is worth it.
Step 1: Whip the Meringue
In a clean bowl (and I mean spotless—any grease ruins meringue), beat the egg whites until foamy. Slowly add sugar and keep whipping until stiff, glossy peaks form. This is the backbone of the cake—it’s what makes it so fluffy.
Step 2: Make the Batter Base
Warm the oil in the microwave for about 90 seconds (or gently on the stove). It should be warm, not sizzling. Stir in the sifted flour and salt until smooth. Then, add egg yolks and milk, whisking until you have a silky, lump-free batter.
Step 3: Fold in the Meringue
Start by mixing in one-third of the meringue to loosen up the batter. Then gently fold in the rest in two more rounds. Use slow, sweeping motions with your spatula—this is not the time for heavy stirring. You’re keeping all that air inside.
Step 4: Pour and Tap
Pour the batter into a parchment-lined loaf or square pan. No greasing the sides—that helps the cake climb while baking. Tap the pan firmly on the counter a few times to pop big air bubbles.
Step 5: Bake in a Water Bath
Here’s the fun part: set your cake pan inside a larger baking dish and pour in hot water until it reaches halfway up the sides. Bake at 300°F (150°C) for about 60 minutes. The top should be golden and the center springy to the touch.
Step 6: Cool and Slice
When it’s done, give the pan a few gentle bangs on the counter to release steam (this keeps it from shrinking). Let it cool in the pan, then move it to a cutting board. Use a serrated knife for clean slices.
Tips for the Best Castella Cake
- Use superfine sugar—it dissolves faster in the meringue.
- Don’t rush the folding—slow and gentle is key.
- Keep the water hot in the water bath, but don’t let it boil over.
- Cool completely before slicing—it’ll be way easier to cut.
Why You’ll Love This Cake
Honestly, this cake is addictive. It’s soft, moist, and has just enough sweetness without being heavy. It’s perfect for birthdays if you’re into something lighter than frosted cake, or just as a weekday treat when you want something a little fancy without going full bakery mode.
And if you’re like me, you’ll sneak that first slice while it’s still warm—patience isn’t always my strong suit.
Final Bite
Making a fluffy Castella sponge cake at home is easier than it looks. With just eggs, sugar, flour, and a little patience, you’ll pull out a cake that’s soft, airy, and absolutely unforgettable. So grab your whisk, preheat that oven, and get ready to taste cake in its fluffiest form.
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