Castella cake (Kasutera) is a moist, fine-grained sponge cake with a distinctively dense crumb and a subtle honey sweetness. Originating from Nagasaki, Japan, it is made from just four ingredients—bread flour, eggs, sugar, and honey (or syrup)—yet its texture is uniquely soft and springy. This recipe replicates the authentic method of mixing the batter until the flour’s gluten develops, which gives the cake its characteristic chew and moistness, while the low-temperature baking ensures it stays tender.
Ingredients
- 6 large eggs (about 300 g / 10.5 oz), at room temperature
- 1 cup (200 g) granulated sugar
- 2 tablespoons (40 g) honey
- 2 tablespoons (30 ml) hot water (about 50°C / 122°F)
- 1 1/2 cups (190 g) bread flour (or all-purpose flour, sifted)
- 1/4 cup (60 ml) milk (optional, for extra moisture)
Instructions
- Preheat your oven to 320°F (160°C). Line a 9×5-inch (23×13 cm) loaf pan with parchment paper, leaving overhang on the long sides for easy removal.
- In a small bowl, dissolve the honey in the hot water. Set aside to cool slightly.
- In a large mixing bowl, combine the eggs and sugar. Place the bowl over a pot of simmering water (double boiler) and whisk gently until the sugar dissolves and the mixture is lukewarm (about 40°C / 104°F).
- Remove the bowl from the 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 triples in volume. When you lift the whisk, the batter should fall in a thick ribbon that holds its shape on the surface for a few seconds.
- Reduce the mixer speed to low and add the honey-water mixture and milk (if using). Mix just until combined.
- Sift the flour into the batter in three additions. Use a rubber spatula to fold gently after each addition, scraping from the bottom to incorporate without deflating the foam. Fold until no streaks of flour remain—about 20–30 strokes per addition.
- Pour the batter into the prepared pan. Tap the pan on the counter a few times to release large air bubbles.
- Bake at 320°F (160°C) for 20 minutes, then reduce the oven temperature to 300°F (150°C) and bake for another 60 minutes. The cake is done when a skewer inserted into the center comes out clean, and the top is deep golden brown.
- Remove 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 before slicing. This step is crucial for achieving the dense, moist texture.
Tips
- Use bread flour: The higher protein content in bread flour creates more gluten, which gives the cake its signature chew. If using all-purpose, the texture will be slightly lighter but still good.
- Do not overfold: Overfolding deflates the batter, resulting in a dense, flat cake. Fold just until no flour is visible.
- Chill before slicing: Refrigerating the cake overnight firms it up, making it easier to cut clean, even slices. It also improves the flavor and texture.
- Substitute honey: If you don’t have honey, use corn syrup or glucose syrup. This will change the flavor slightly but still produce a moist cake.
Serving Suggestions
Serve castella cake at room temperature with a cup of green tea or coffee. It’s also delicious lightly toasted and spread with butter or jam. For a dessert, pair it with fresh berries and a dollop of whipped cream.
Variations
- Matcha Castella: Replace 1 tablespoon of flour with 1 tablespoon of matcha powder for a green tea version.
- Chocolate Castella: Replace 2 tablespoons of flour with 2 tablespoons of unsweetened cocoa powder.
- Brown Sugar Castella: Substitute half the granulated sugar with brown sugar for a deeper, caramel-like flavor.
Storage and Reheating
Store the cake wrapped in plastic wrap in the refrigerator for up to 5 days. It can also be frozen for up to 1 month—wrap tightly in plastic and foil, then thaw in the refrigerator overnight. To reheat, microwave a slice for 10–15 seconds or warm in a toaster oven at 300°F (150°C) for 5 minutes. The cake is best served at room temperature or slightly warm.
Frequently Asked Questions
Why is my castella cake too dense or flat? This usually happens when the egg foam is deflated during folding. Be gentle and fold only until the flour is incorporated. Also, ensure the eggs are beaten to the ribbon stage before adding the flour.
Can I use cake flour instead of bread flour? Cake flour has less protein, so the cake will be softer and less chewy. It will still taste good, but the texture will be closer to a traditional sponge cake.
Why do I need to refrigerate the cake before slicing? Refrigerating firms the crumb, making it easier to cut neat slices without tearing. It also allows the flavors to meld and the moisture to distribute evenly.
Can I make this without a mixer? Yes, but it will require vigorous whisking by hand for about 15–20 minutes to achieve the ribbon stage. It’s a good arm workout!
Why is the top of my cake sticky? A slightly sticky top is normal for castella, especially if you covered it with plastic wrap while warm. This is actually desirable—it adds to the moistness. If you prefer a dry top, skip the plastic wrap and let it cool uncovered.
Can I reduce the sugar? Sugar is essential for the texture and moisture of this cake. Reducing it significantly will make the cake drier and less tender. You can try cutting it by 10–20% without major issues, but the texture will change.
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