Castella cake is a soft, moist Japanese sponge cake made from just four ingredients: flour, eggs, sugar, and honey. It has a dense, velvety crumb and a slightly sweet, honeyed flavor that makes it a popular treat in the UK, especially in Japanese bakeries. This recipe recreates that authentic texture at home using standard UK ingredients and a simple water bath method.
Ingredients
- 6 large eggs (300 g / 10.5 oz), at room temperature
- 200 g (1 cup) caster sugar
- 100 g (3.5 oz) strong white bread flour (or plain flour, see Tips)
- 2 tablespoons (30 ml) honey
- 2 tablespoons (30 ml) warm water
- 1 teaspoon lemon juice (optional, for stabilising)
- Butter or oil, for greasing the tin
Instructions
- Preheat your oven to 160°C (320°F). Grease a 20 cm (8 inch) square or round cake tin and line the bottom and sides with baking parchment. If using a springform tin, wrap the outside with foil to prevent water seeping in.
- In a small bowl, mix the honey with the warm water until dissolved. Set aside.
- Separate the eggs: put the whites in a large mixing bowl and the yolks in a separate small bowl. Beat the yolks lightly with a fork.
- Using an electric mixer, whisk the egg whites on medium speed until frothy. Gradually add the sugar, a spoonful at a time, while continuing to whisk. Increase the speed to high and beat until stiff, glossy peaks form (about 5–7 minutes). The meringue should be firm enough that when you lift the whisk, the peaks hold their shape.
- With the mixer on low speed, add the egg yolks one at a time, beating well after each addition. Then pour in the honey-water mixture and the lemon juice (if using). Beat for another minute until fully combined.
- Sift the flour over the batter in three additions. Using a large metal spoon or spatula, fold gently after each addition. Fold just until no streaks of flour remain; do not overmix, or the cake will be tough.
- Pour the batter into the prepared tin. Tap the tin on the counter a few times to release any large air bubbles.
- Place the cake tin in a larger roasting pan. Fill the roasting pan with hot water until it comes about 2 cm (1 inch) up the sides of the cake tin. This water bath keeps the cake moist and prevents it from cracking.
- Bake for 60–65 minutes, until the top is golden brown and a skewer inserted into the centre comes out clean. The internal temperature should read at least 160°F (71°C) if you use a food thermometer (this is the safe minimum for egg dishes).
- Turn off the oven and leave the cake inside with the door slightly ajar for 10 minutes. This helps prevent the top from sinking.
- Remove the cake from the water bath and let it cool in the tin for 15 minutes. Then lift it out using the parchment, peel off the paper, and cool completely on a wire rack.
- Once cool, wrap the cake in cling film and refrigerate for at least 1 hour before slicing. This firms it up and makes clean, even slices.
Tips
- Flour: Strong bread flour gives a chewier, more authentic texture. If you only have plain flour, the cake will be slightly lighter and more delicate – still delicious.
- Room temperature eggs: Cold eggs don’t whip as well. Take them out of the fridge 30 minutes before starting.
- Water bath: Don’t skip it – it’s essential for the moist, tender crumb. Make sure the foil around your tin is watertight.
- Cutting: Use a serrated knife and wipe it clean between cuts for neat slices. Chilling the cake first makes this much easier.
Serving Suggestions
Castella is delicious on its own with a cup of green tea or coffee. For a dessert, serve slices with fresh strawberries and lightly whipped cream. In Japan, it’s often enjoyed as a snack with milk or as part of a bento box.
Variations
- Matcha Castella: Replace 1 tablespoon (10 g) of the flour with matcha powder for a green tea version.
- Chocolate Castella: Replace 20 g (0.7 oz) of flour with cocoa powder.
- Honey-free: Substitute the honey with golden syrup or maple syrup for a different sweetness.
Storage and Reheating
Store the cake in an airtight container at room temperature for up to 3 days, or in the fridge for up to a week. It also freezes well for up to 2 months – wrap tightly in cling film and thaw overnight in the fridge. To serve, bring to room temperature or warm slices in a toaster for 1–2 minutes for a fresh-baked feel.
Frequently Asked Questions
Why did my cake sink in the middle?
This usually happens if the batter was overmixed, which deflates the air bubbles, or if the oven door was opened during baking. Make sure to fold gently and keep the oven closed until at least 50 minutes have passed.
Can I use a hand mixer instead of a stand mixer?
Yes, a hand mixer works fine. Just be prepared to hold it for a few extra minutes – the meringue needs to be very stiff.
Why is my castella too dense or rubbery?
Overmixing the flour or under-whipping the eggs are the usual culprits. Fold until just combined, and beat the meringue until it holds a stiff peak that doesn’t droop.
Can I make this without a water bath?
You can, but the cake will be drier and more likely to crack. The water bath is key to the signature moist texture.
How do I know when it’s done?
A skewer inserted into the centre should come out clean, and the top should be golden. If you have a thermometer, the centre should read 160°F (71°C) – the safe minimum for egg dishes.
Can I use all-purpose flour instead of bread flour?
Yes, plain/all-purpose flour works. The texture will be slightly softer and less chewy, but still very good.
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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes
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