Castella cake (Kasutera) is a Japanese sponge cake made from just four ingredients—eggs, sugar, flour, and honey (or sometimes mirin)—baked slowly until it develops its signature dense, moist crumb and deep golden-brown top. It’s a beloved confection that originated from Portuguese influence in Nagasaki in the 16th century, and today it’s enjoyed as a tea-time treat or a gift. The cost of making castella at home is surprisingly low—about $3–$4 for a standard loaf—compared to buying a store-bought version, which can cost $8–$15. This recipe delivers a classic, authentic texture with a crisp top and tender interior, using simple pantry staples and a water bath to ensure even baking.
Ingredients
- 6 large eggs (about 300 g, room temperature)
- 1 cup (200 g) granulated sugar
- 2 tablespoons (40 g) honey (or 1 tablespoon honey + 1 tablespoon mirin)
- 1 cup (125 g) cake flour (see Tips for substitution)
- 2 tablespoons (30 ml) milk (optional, for softer crumb)
- 1 tablespoon (15 ml) vegetable oil (optional, for moisture)
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 removal.
- In a large mixing bowl, combine the eggs and sugar. Place the bowl over a pot of simmering water (double boiler) and whisk constantly until the sugar dissolves and the mixture feels warm to the touch (about 100°F / 38°C). This step helps the eggs whip to a stable foam.
- Remove the bowl from the heat. Using a hand mixer or stand mixer, beat the egg mixture on high speed for 8–10 minutes, until it becomes thick, pale, and triples in volume. When you lift the whisk, the batter should fall in a thick ribbon that holds its shape for a few seconds.
- In a separate small bowl, warm the honey (and mirin if using) with the milk and oil (if using) until runny—about 15 seconds in the microwave or over the double boiler. Set aside.
- While the mixer is on low speed, slowly add the honey mixture to the beaten eggs, mixing just until combined. Turn off the mixer.
- Sift the cake flour over the batter in three additions. Use a rubber spatula to fold gently after each addition, cutting down the middle and scraping the bottom of the bowl to avoid deflating the batter. Fold until no streaks of flour remain, but do not overmix.
- Pour the batter into the prepared pan. Tap the pan on the counter a few times to release large air bubbles.
- Place the loaf pan inside a larger roasting pan. Fill the roasting pan with hot water until it reaches about 1 inch (2.5 cm) up the sides of the loaf pan. This water bath helps the cake bake evenly and keeps it moist.
- Bake for 60–70 minutes, or until the top is deep golden brown and a skewer inserted into the center comes out clean. If the top browns too quickly, loosely cover with foil after 40 minutes.
- Remove the loaf pan from the water bath and let it cool in the pan for 10 minutes. Then lift it out using the parchment overhang and transfer to a wire rack. Cool completely before slicing.
- For best texture, wrap the cake tightly in plastic wrap and let it rest at room temperature for 6–8 hours or overnight. This allows the moisture to distribute evenly and the crumb to become more tender.
Tips
- Flour substitution: If you don’t have cake flour, use 1 cup (125 g) all-purpose flour minus 2 tablespoons (16 g), and replace with 2 tablespoons (16 g) cornstarch. This mimics the lower protein content of cake flour.
- Honey vs. mirin: Traditional castella uses honey, but some versions use mirin (sweet rice wine) for a subtler sweetness. You can use all honey, all mirin, or a mix—just keep the total liquid amount the same.
- Don’t overmix: Overfolding the flour will deflate the batter and result in a dense, rubbery cake. Fold just until the flour disappears.
- Water bath: Don’t skip the water bath—it’s essential for the cake’s characteristic moist, tender crumb. If you don’t have a roasting pan, place a small oven-safe dish with water on the rack below the cake.
Serving Suggestions
Slice the castella into thick, even pieces and serve with green tea (matcha or sencha) for a classic Japanese tea-time treat. It also pairs beautifully with fresh fruit like strawberries or a dollop of whipped cream. For a dessert twist, toast slices lightly and top with ice cream or a drizzle of honey.
Variations
- Matcha Castella: Replace 1 tablespoon (8 g) of the cake flour with matcha powder and sift together. This gives a vibrant green color and earthy flavor.
- Brown Sugar Castella: Substitute half the granulated sugar with brown sugar for a deeper, caramel-like flavor.
- Chocolate Castella: Replace 2 tablespoons (16 g) of flour with unsweetened cocoa powder. Add 1 tablespoon (15 ml) extra milk to keep the batter moist.
- Citrus Castella: Add 1 tablespoon of yuzu juice or orange zest to the honey mixture for a refreshing twist.
Storage and Reheating
Castella keeps well at room temperature for 3–4 days when wrapped tightly in plastic wrap. For longer storage, wrap it in plastic and then foil, and freeze for up to 2 months. Thaw overnight in the refrigerator before serving. To refresh a day-old slice, microwave it for 10–15 seconds or toast lightly—this restores some softness, though the cake is traditionally enjoyed at room temperature.
Frequently Asked Questions
Why is my castella cake too dense or flat? This usually happens when the egg foam is deflated during folding or when you overmix after adding the flour. Be gentle and fold only until no flour streaks remain. Also, ensure the eggs are whipped to the ribbon stage before proceeding.
Can I use a hand whisk instead of an electric mixer? Yes, but it will take much longer—about 20–25 minutes of vigorous whisking. An electric mixer is highly recommended for consistent results.
Why does my cake have a sticky top? A sticky, glossy top is actually a sign of a good castella—it comes from the honey and sugar. If you prefer a drier top, you can bake without the water bath for the last 10 minutes, but be careful not to overcook.
Can I make this without a water bath? You can, but the cake will be drier and less tender. The water bath keeps the oven humid, which is essential for the cake’s signature texture.
How do I know when it’s done? The top should be deep golden brown, and a skewer inserted in the center should come out clean. If the top is browning too fast, cover with foil and continue baking.
Can I reduce the sugar? Sugar is crucial for structure and moisture in this cake. Reducing it too much will result in a drier, less tender crumb. You can reduce by up to 20% (to ¾ cup / 150 g) without major issues.
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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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