Ingredients

• 4 large eggs (200g), at room temperature
• 140g granulated sugar (1 cup + 1 tablespoon)
• 130g cake flour (1 cup + 2 tablespoons), sifted
• 20g milk (4 teaspoons), at room temperature
• 40g neutral oil (about 2 ⅔ tablespoons), such as canola or vegetable oil
• ¼ teaspoon vanilla extract (optional, for extra aroma)

Instructions

Step 1: Prepare Your Ingredients and Tools

1. Preheat the oven to 170°C (338°F). Prepare a square or rectangular cake pan by lightly greasing and lining it with parchment paper, allowing excess paper to overhang for easy removal.
2. Separate the eggs if you prefer a lighter, fluffier texture (optional step). Separate the egg yolks and whites, placing them in clean, grease-free bowls.
3. Warm the milk and oil slightly (not hot) to ensure they incorporate smoothly. Mix in the vanilla extract with the milk if you’re using it.

Step 2: Make the Batter

1. Whip the eggs and sugar: In a large bowl, add the whole eggs (or egg yolks if separated) and sugar. Using an electric mixer on high speed, beat until the mixture triples in volume, becomes pale, and forms a thick ribbon when the beater is lifted (about 7-10 minutes).
   • If using separated eggs: Beat the egg whites separately until they form soft peaks, and gently fold them into the egg yolk mixture after the sugar has been incorporated. This creates an airy texture.
2. Fold in the flour: Sift the cake flour into the egg mixture in batches. Use a spatula to gently fold in the flour after each addition, taking care not to deflate the batter. Continue until all the flour is incorporated and the batter is smooth.
3. Add the milk and oil: Pour the warmed milk and oil mixture down the side of the bowl, then gently fold it into the batter until evenly combined. Avoid overmixing, as this can deflate the airy batter.

Step 3: Bake the Cake

1. Pour and smooth: Pour the batter into the prepared cake pan, smoothing the top with a spatula.
2. Bake: Place the pan in the oven and reduce the temperature to 160°C (320°F). Bake for 35-40 minutes, or until the cake is golden brown, springy to the touch, and a toothpick inserted into the center comes out clean.
3. Cool and remove: Once baked, allow the cake to cool in the pan for about 10 minutes. Use the parchment overhang to lift the cake out and transfer it to a wire rack to cool completely.

Step 4: Slice and Serve

1. Trim edges (optional): For a traditional presentation, trim the edges of the cake to reveal the soft, moist interior.
2. Slice and enjoy: Slice the cake into squares or rectangles. Serve plain, with a dusting of powdered sugar, or alongside fresh fruit and whipped cream for a delightful treat.

Nutrition Facts (approximate per slice, assuming 8 slices)

• Calories: 160
• Protein: 4g
• Fat: 7g
• Carbohydrates: 21g
• Fiber: 0.5g
• Sugars: 12g
• Sodium: 20mg

Note: Nutritional values may vary slightly based on ingredient brands and serving sizes.

FAQ

1. Can I use all-purpose flour instead of cake flour?
Yes, though cake flour is preferred for its low protein content, which gives the cake its delicate, fluffy texture. If you only have all-purpose flour, replace each cup with 1 cup minus 2 tablespoons of all-purpose flour, then add 2 tablespoons of cornstarch.

2. Why did my cake sink in the middle?
This could be due to overmixing the batter or baking at too high a temperature. Always fold gently and bake at a consistent low temperature to prevent deflation.

3. Can I make Castella cake ahead of time?
Yes! In fact, allowing it to rest overnight enhances the flavor. Wrap the cooled cake tightly in plastic wrap and store at room temperature for up to 2 days.

4. How can I add more flavor to this cake?
Adding matcha powder, lemon zest, or even honey can add subtle new flavors. If using matcha, sift in about 1-2 teaspoons with the flour for a green tea twist.

5. Why separate the eggs?
Separating the eggs and whipping the whites into soft peaks before folding into the batter helps achieve a very light, airy texture in the cake.

Tips for Making the Best Castella Cake

1. Room Temperature Ingredients: Use room-temperature eggs, milk, and oil. Cold ingredients can affect the cake’s rise and texture.
2. Beat until ribbon stage: When beating the eggs and sugar, make sure to reach the ribbon stage, where the mixture falls in thick ribbons from the beaters and holds shape briefly before sinking back. This aeration gives the cake its light texture.
3. Avoid overmixing: Gently fold the flour and liquid ingredients to prevent deflating the whipped eggs. Overmixing will create a dense, heavy cake.
4. Use a water bath (optional): Placing the cake pan in a water bath during baking helps keep the cake moist and prevents it from cracking on top.
5. Cool gradually: Let the cake cool gradually to prevent sinking. Leaving it in the pan for 10 minutes before transferring to a wire rack helps stabilize the structure.

Storage Tips

Room Temperature: Store the cake at room temperature, tightly wrapped in plastic wrap or in an airtight container, for up to 2 days. This resting time actually improves the flavor and texture, making it even softer and more flavorful.

Refrigerator: While not necessary, you can refrigerate the cake for up to 5 days. Allow it to come to room temperature before serving, as refrigeration can slightly firm the texture.

Freezer: Wrap slices individually in plastic wrap and place them in a freezer-safe bag. Store for up to 1 month. Thaw at room temperature before serving.

Conclusion

Japanese Castella Cake is a timeless dessert that showcases the beauty of simple ingredients and precise technique. With its light, airy structure and subtly sweet flavor, this sponge cake is ideal for any occasion. Mastering the Castella cake requires a bit of patience and care in folding and baking, but the results are well worth it. Whether enjoyed plain or with a dollop of whipped cream and fresh fruit, this cake is a testament to the art of minimalism in baking. Serve it as a delightful end to a meal, or enjoy a slice with your favorite tea or coffee—it’s a treat that’s sure to impress!