Castella Cake, known as Kasutera (カステラ) in Japan, is one of the country's most beloved traditional sponge cakes. Famous for its moist texture, delicate sweetness, and beautifully golden crust, Castella has been enjoyed for centuries as both a tea-time treat and a thoughtful gift. Unlike Western sponge cakes that rely on butter or oil, Castella gets its rich texture from carefully whipped eggs, sugar, flour, and honey.

This elegant cake originated in Nagasaki after Portuguese merchants introduced sponge cake to Japan in the 16th century. Japanese bakers refined the recipe over time, creating a lighter, sweeter version that has become an iconic dessert throughout Japan.

Whether served with green tea, coffee, or black tea, homemade Castella Cake offers a delightful balance of simplicity and sophistication.

What is Japanese Castella Cake?

Castella is a traditional Japanese sponge cake made with:

  • Eggs
  • Bread flour
  • Sugar
  • Honey
  • Milk

Unlike chiffon or butter cakes, Castella contains no baking powder or butter. The cake rises entirely from the air incorporated into whipped eggs, creating its signature soft, fine crumb.

The bottom of authentic Castella often develops a slightly chewy layer thanks to coarse sugar placed beneath the batter before baking.

Ingredients

For the Cake

  • 6 large eggs (room temperature)
  • 200 g granulated sugar
  • 2 tablespoons honey
  • 2 tablespoons warm milk
  • 200 g bread flour (sifted)
  • 1 teaspoon vanilla extract (optional)

Optional Bottom Layer

  • 2 tablespoons coarse sugar

Equipment Needed

  • 8-inch square baking pan
  • Parchment paper
  • Electric mixer
  • Mixing bowls
  • Fine sieve
  • Rubber spatula
  • Cooling rack

Preparation Time

  • Preparation: 20 minutes
  • Mixing: 15 minutes
  • Baking: 50 minutes
  • Cooling: 2 hours

Total Time: Approximately 3 hours 30 minutes

Servings: 10 slices

Step-by-Step Instructions

Step 1: Prepare the Baking Pan

Preheat the oven to 160°C (320°F).

Line the baking pan completely with parchment paper, allowing extra paper to extend above the edges.

If desired, sprinkle coarse sugar evenly across the bottom.

Step 2: Mix Honey

Combine:

  • Honey
  • Warm milk

Stir until smooth.

Set aside.

Step 3: Beat the Eggs

Place eggs in a large mixing bowl.

Add sugar gradually while beating with an electric mixer.

Continue beating for 8–10 minutes until:

  • Pale yellow
  • Thick
  • Tripled in volume

The batter should leave ribbons when lifted.

Step 4: Fold in Flour

Sift bread flour into the egg mixture in several additions.

Using a spatula, gently fold without deflating the batter.

Avoid vigorous mixing.

Step 5: Add Honey Mixture

Pour the honey mixture around the edge of the bowl.

Fold gently until evenly incorporated.

Step 6: Pour into Pan

Transfer batter into the prepared pan.

Tap the pan gently to remove large air bubbles.

Use a skewer to swirl through the batter to eliminate hidden bubbles.

Step 7: Bake

Bake for 50–55 minutes.

The cake is ready when:

  • Top is golden brown
  • Center springs back lightly
  • Toothpick comes out clean

Step 8: Cool Properly

Remove from oven.

Drop the pan gently from about 10 cm (4 inches) onto the counter to minimize shrinkage.

Remove cake from pan.

Wrap the warm cake tightly in plastic wrap.

Allow it to cool completely.

Refrigerate overnight for the best texture.

Why Refrigerate Overnight?

Traditional Japanese bakeries rest Castella overnight because it:

  • Redistributes moisture
  • Enhances honey flavor
  • Softens the crumb
  • Creates the signature silky texture

Tips for Perfect Castella

Use Bread Flour

Bread flour provides the chewy softness unique to Castella.

Room Temperature Eggs

They whip faster and create greater volume.

Fold Carefully

Do not stir aggressively.

The trapped air creates the cake's rise.

Bake Slowly

Lower temperatures ensure even baking without cracking.

Wrap While Warm

This locks in moisture and keeps the cake exceptionally soft.

Traditional Japanese Serving Style

Castella is usually served:

  • Cut into thick rectangular slices
  • With hot green tea
  • Alongside matcha
  • With black tea
  • With coffee

No frosting or decorations are needed.

Flavor Variations

Matcha Castella

Mix:

  • 2 tablespoons matcha powder

with the flour.

Chocolate Castella

Replace:

  • 25 g flour

with cocoa powder.

Brown Sugar Castella

Replace white sugar with Japanese brown sugar for deeper flavor.

Yuzu Castella

Add:

  • 1 tablespoon yuzu zest

for a refreshing citrus aroma.

Black Sesame Castella

Fold in:

  • 2 tablespoons toasted black sesame paste

Earl Grey Castella

Add finely ground Earl Grey tea leaves for a fragrant twist.

Storage Tips

Room temperature:

  • 3 days in an airtight container

Refrigerator:

  • Up to 1 week

Freezer:

  • Up to 2 months

Wrap individual slices before freezing.

Nutritional Information (Per Slice)

  • Calories: 210
  • Protein: 6 g
  • Carbohydrates: 34 g
  • Fat: 5 g
  • Sugar: 22 g
  • Fiber: 1 g
  • Sodium: 65 mg

Common Mistakes to Avoid

  • Using cold eggs
  • Overmixing after adding flour
  • Opening the oven too early
  • Underbaking the center
  • Skipping the overnight resting period
  • Not removing air bubbles before baking

Frequently Asked Questions

Why is Castella made with bread flour?

Bread flour contains more protein than cake flour, giving Castella its signature slightly chewy yet tender texture.

Can I use cake flour instead?

Yes, but the cake will be lighter and softer, with less of the traditional Castella chew.

Why doesn't Castella contain butter?

Traditional Japanese Castella relies on whipped eggs rather than fat for its airy structure, resulting in a clean, delicate flavor.

Can I make it without honey?

Yes. Substitute honey with an equal amount of light corn syrup or sugar syrup, though honey contributes a distinctive aroma and moisture.

Why did my cake collapse?

Common causes include underwhipped eggs, overmixing after adding flour, or removing the cake from the oven before it is fully baked.

Final Thoughts

Japanese Castella Cake is a timeless dessert that highlights the beauty of simple ingredients and careful technique. With its delicate honey aroma, moist crumb, and elegant presentation, it has remained a favorite in Japan for generations. Whether enjoyed as an afternoon snack with tea or shared as a homemade gift, this classic sponge cake brings a touch of Japanese tradition to any table. By allowing the cake to rest overnight, you'll achieve the signature soft, silky texture that makes authentic Castella so memorable.