Castella Cake in Japanese: Authentic Recipe

Castella cake (kasutera) is a classic Japanese sponge cake with Portuguese roots, known for its fine, even crumb and subtly sweet honey flavor. Unlike airy Western sponges, this cake is dense, moist, and slightly springy, with a caramelized bottom crust that adds a lovely contrast. This recipe uses the traditional method of beating whole eggs with sugar until thick, then folding in flour and honey, which yields a cake that tastes like the ones from Nagasaki’s famous bakeries.

Ingredients

6 large eggs (about 300 g / 10.5 oz), at room temperature
1 cup (200 g) granulated sugar
1 cup (120 g) bread flour (or all-purpose flour for a slightly softer crumb)
2 tbsp (40 g) honey
2 tbsp (30 ml) whole milk
1 tbsp (15 ml) mirin (optional, adds subtle sweetness and moistness)

Instructions

Preheat your oven to 320°F (160°C). Line a 9×5-inch (23×13 cm) loaf pan with parchment paper, leaving some overhang on the long sides for easy lifting.
In a heatproof bowl, combine the eggs and sugar. Place the bowl over a pot of simmering water (make sure the bottom doesn’t touch the water) and whisk gently until the sugar dissolves and the mixture feels lukewarm to the touch, about 2-3 minutes. Remove from heat.
Using a hand mixer or stand mixer, beat the egg mixture on high speed for about 8-10 minutes, until it becomes thick, pale, and holds a ribbon pattern when you lift the beaters. The batter should fall back in a slow, thick ribbon that stays on the surface for a few seconds.
In a small bowl, mix the honey, milk, and mirin (if using) until well combined.
Sift the flour into the egg mixture in two additions, folding gently with a rubber spatula after each addition. Fold just until no streaks of flour remain—do not overmix, or the cake will lose its rise.
Take about 1 cup of the batter and fold it into the honey-milk mixture until smooth. Then pour this mixture back into the main batter and fold gently until fully incorporated.
Pour the batter into the prepared pan. Tap the pan firmly on the counter a few times to release any large air bubbles. Use a skewer or toothpick to pop any bubbles that rise to the surface.
Bake for 50-55 minutes, until the top is deep golden brown and a skewer inserted into the center comes out clean. The internal temperature should reach 200°F (93°C) for a fully set crumb (this is not a food safety requirement, but a doneness indicator).
Remove the cake from the oven and immediately cover the pan with plastic wrap (this traps steam and keeps the cake moist). Let it cool completely in the pan, about 1 hour.
Once cool, lift the cake out using the parchment overhang. Wrap it tightly in plastic wrap and refrigerate for at least 4 hours or overnight. This step is essential—it firms the crumb and makes it easier to slice cleanly.
When ready to serve, trim the dark crusty edges, then slice into even pieces. Serve at room temperature.

Tips

Use fresh eggs: Fresh eggs create a more stable foam, which gives the cake its fine, even texture. Older eggs may deflate more easily.
Don’t skip the refrigeration: Chilling the cake overnight is the secret to that dense, moist texture. It also makes slicing much easier without crumbling.
Substitute for mirin: If you don’t have mirin, replace it with 1 tablespoon (15 ml) of water plus 1/2 teaspoon of sugar. The flavor will be slightly less complex but still good.
Flour choice: Bread flour gives a chewier, more traditional texture. All-purpose flour works but yields a softer, more tender cake. Do not use cake flour—it will make the cake too delicate.

Serving Suggestions

Castella is delicious on its own with a cup of green tea or coffee. For a richer treat, serve it with a dollop of whipped cream and fresh strawberries. Some people enjoy it lightly toasted, which brings out the honey flavor and adds a slight crunch to the edges. In Japan, it’s often given as a gift, so you can wrap individual slices in decorative paper.

Variations

Matcha Castella: Replace 2 tablespoons (15 g) of flour with matcha powder and sift together. Add a bit of extra honey (1 teaspoon) to balance the bitterness.
Chocolate Castella: Replace 3 tablespoons (20 g) of flour with unsweetened cocoa powder. You may need to add an extra tablespoon of milk to keep the batter moist.
Brown Sugar Castella: Use 1/2 cup (100 g) granulated sugar and 1/2 cup (100 g) packed brown sugar for a deeper, caramel-like flavor.

Storage and Reheating

Store castella in an airtight container at room temperature for up to 3 days, or in the refrigerator for up to 1 week. It also freezes well for up to 2 months—wrap tightly in plastic wrap and then foil. To thaw, leave it in the refrigerator overnight. While castella is best at room temperature, you can reheat individual slices in a toaster oven at 300°F (150°C) for 3-4 minutes to refresh the texture, but avoid microwaving as it will make the cake rubbery.

Frequently Asked Questions

Why is my castella cake dense or not fluffy? The most common cause is under-whipping the eggs. You need to beat them until they reach the ribbon stage—when the batter falls in a thick ribbon that holds its shape for a few seconds. If the batter is too thin, the cake will be dense. Also, fold the flour gently to avoid deflating the foam.

Can I use a hand mixer instead of a stand mixer? Yes, a hand mixer works fine, but it will take longer—about 10-12 minutes. Make sure to use a large bowl and move the beaters around to incorporate air evenly.

My cake has a strong eggy smell. How can I avoid that? Use fresh eggs and make sure they are at room temperature. The honey also helps mask the egg flavor. Some bakers add a teaspoon of vanilla extract or a pinch of salt to balance the aroma.

Why did my cake collapse after baking? This usually happens if you open the oven door during baking, or if the cake is underbaked. Always bake until a skewer comes out clean and the top is a deep golden brown. Also, let the cake cool gradually in the pan with plastic wrap—sudden temperature changes can cause sinking.

Can I make this cake without honey? Yes, you can substitute the honey with equal parts of corn syrup or maple syrup. Keep in mind that the flavor and moisture will change slightly. For a traditional taste, honey is best.

Is it necessary to use bread flour? No, but it gives a more authentic texture—chewy and slightly dense. If you only have all-purpose flour, it will still work, just expect a softer cake. Avoid cake flour as it will make the cake too fragile.

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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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