Single flavored kasutera, check! Double-flavored marbled kasutera, check! I did not make this one but it is out there. And now I present to you the triple-flavored Neapolitan Kasutera! Achoo…talk about a persistent bug! This one shows no sign of abating. Have no fear though as this bug should not harm you unless you over-indulge. In fact, you may actually hope to catch it. :)

Neapolitan ice cream is a tri-colored combination of flavors, usually consisting of chocolate, vanilla, and strawberry ice cream in a single block. Adapting it to a cake baked in a single pan was quite a challenge but the result was pleasing to the eye and the taste combination delightful. The three separate flavors of different consistencies can be placed side by side into a single cake pan without them mixing together. Though not perfect, the tri-colored effect can definitely be achieved…YAY!

So, how did I prevent the three layers from mixing together? I used the Divider Method as described here. Making two flavors in a wide pan would be a lot easier. I wasn’t sure if three narrow strips would work as there was very little room for the batter to spread before it all got “messed” up. There was only one way to find out. I cut out two cardboard dividers and covered them with aluminum foil. Since I did not have a helper to hold up the dividers, I had to make sure they fitted snugly in the pan so that they could stand on their own.

After removing the dividers, the pan should be placed immediately into preheated oven. Needless to say I was frantic having to pause for pictures. As you can see, the different layers of batter were already starting to spread.

To make the three different flavors, I divided the base batter (after addition of mirin) into three equal portions of 4½oz (130g) each. Then I stirred in a little over a tablespoon cocoa mixture into one portion and honey mixture into another portion. The strawberry flavor was tricky. I felt that a tablespoon of strawberry would not be sufficient. Hence, I added all three tablespoons yielded from cooking down the sauce plus two drops of red food coloring to intensify the color. However, this meant that the strawberry batter would have a little more volume because of the additional liquid. Misjudging the appearance of the strawberry layer, I made the mistake of removing two tablespoons of the batter out of the pan resulting in the “wave” you see on the strawberry portion of the cake after baking. It was as if there was insufficient batter there. The top was smooth with very little to no shrinkage.

Apart from its wavy appearance, I must say this cake had the best flavor and texture compared to the Honey Kasutera and Matcha Kasutera I had made previously. The texture was very fine and a little more dense than the previous two cakes. This cake was moist and the mirin was definitely discernible. The strawberry flavor had a very mild tartness to it and combined well with the cocoa and honey flavors. I was more than happy.

For a kasutera that is even more Drop-Dead-Delicious, it must be given the customary “drop treatment”! I found this interesting study paper, Prevention of Shrinkage After Baking by H. Ohtsubo, T. Kanbe, Y. Kaneko, and S. Nomura explaining the physics of the “drop treatment”. In essence, baking causes expansion of cell walls in the cake until it hardens into rigid cells. As the cake cools, the pressure drops and no longer supports those walls causing shrinkage. A mechanical shock treatment applied to the cake immediately after baking cracks the cell walls relieving the pressure instantaneously to pre-empt the effects of shrinkage. Brilliant!

When dropping the cake, the traditional accompanying martial art’s cry kiai (気合) is highly optional but recommended as it may instantaneously release the pent up pressure within YOU! ;)

Neapolitan Kasutera (Neapolitan Castella)

Prep Time: 30 minutes

Cook Time: 45 minutes

Yield: 1 8¾in x 3¼in cake

Neapolitan Kasutera (Neapolitan Castella)


  • 2/3 cup (100g) bread flour, sifted
  • 4 egg whites at room temperature
  • 4 egg yolks at room temperature
  • ½ cup (110g) sugar
  • 2 tbsp mirin
  • 1 tbsp cocoa powder
  • 1 tsp honey
  • Strawberry Sauce
  • 5oz (150g) strawberries, hulled and quartered
  • 1 tsp sugar
  • 3 tbsp water
  • 2 drops red food coloring


Line an 8¾in x 3¼in (22½cm x 8cm) loaf pan with aluminum foil. Cut two pieces of cardboard the width and height of the loaf pan to act as separators. Wrap cardboard separators with aluminum foil and place them equally spaced in the pan.

Place strawberries, sugar, and water in a small saucepan over medium heat. Mash strawberries with spatula and cook till thick and syrupy, about 8 minutes. Strain mixture, pressing with spatula to extract the juice. Discard pulp.

Stir cocoa powder with 1 tablespoon hot water in a small bowl till well combined. In another small bowl, combine honey with 1 tablespoon hot water.

Preheat oven to 325°F (165°C).

Place egg whites in mixing bowl and beat at high speed (speed 10*) for 30 seconds until slightly foamy. Add sugar in 2 to 3 increments until firm peaks form, about 4 minutes.

Add yolks one at a time at medium low speed (speed 4*) until well combined, about 1 minute. Add sifted bread flour and beat until just combined. Add mirin and continue to beat for another minute.

Pour batter through a sieve into a large bowl. Press with a spatula to help batter go through sieve.

Divide batter equally into 3 portions of 4½ oz (130g) each into 3 separate bowls. Add strawberry sauce (about 3 tablespoons) and 2 drops of red food coloring to one of the bowls and gently stir with a spatula till well combined. Repeat with cocoa mixture and honey mixture.

Pour each of the flavored batter into each section of the prepared loaf pan. Tap pan on the counter to remove air bubbles. Pull out both cardboard separators and immediately place into preheated oven. Bake for 45 minutes or until top is evenly browned. Toothpick inserted into cake should come out clean.

Remove pan from oven and drop it from a one foot height onto the counter to prevent shrinkage. Place a piece of parchment paper on a large piece of shrink wrap. When cake is cool enough to handle, lift cake up by holding the edge of aluminum foil. Turn cake upside down onto parchment paper. Peel off aluminum foil. Wrap shrink wrap over cake and leave overnight in the refrigerator (right side up) to preserve moisture in the cake and for flavor to develop. Alternatively, warm cake can put into a Ziploc bag with the foil and left in the refrigerator (right side up) overnight.

To serve, cut off edges on three sides except the browned top with a very sharp knife. Cut into thick slices using a sawing motion and serve with a cup of tea.

Feedback from the field indicates that the previous two recipes were too sweet for some and too light for others. Can’t please everyone but glad to hear many LOVED it and have made it successfully! A few even made it repeatedly. :) This Neapolitan Kasutera is the culmination of my three attempts and I think it has the best texture and flavor. I would highly recommend adding the mirin. It wasn’t in my honey kasutera because I was distracted with taking the step-by-step pictures and only realized the omission after the batter was in the pan. Below is the summary of my adjusted recipes for the different pan sizes. Use only one flavoring for each of the cakes. Please adjust the measurements of the flavorings accordingly if you intend to split the batter into two or three flavors.

The other two cakes… Please click on the picture to get to the post.

Finally, the key to a successful kasutera is patience. I know it is hard to refrain from eating the cake when it is fresh out of the oven but you will be glad you did. Wrap up the cake while still slightly warm and keep it in the refrigerator overnight. This finishing touch improves its moistness. Some have placed it upside down with no adverse effects while others placed it right side up in the fridge. I had the problem of the top of the cake sticking to the parchment paper and so I prefer to place it right side up with the parchment paper loosely covering the top.

I would like to mention here that my recipes are based on the original from
Yummy Workshop
who adapted and simplified the steps from another recipe found on this Japanese
Youtube video.
I also implemented some tips from
Just Hungry.

For the most beautiful Matcha Marble Castella Cake ever, please check out my friend’s blog
Anncoo Journal.

Achoo… I hope you catch the bug! ;) Happy Baking!

Enjoy…..and have a wonderful day! 8)