Would you believe there is such a thing as a “kasutera bug”? It seems to have gone viral again in the food blogosphere. I was told it made an appearance some years back where there was a frenzy of “kasuteritis”. Symptoms varied from deep despondence over sunken sponges to giddying heights over light and fluffy delights. Then there is the case of the perfectly smooth brown top versus the wrinkled martian landscape. The latter being much cause for the wringing of hands. If that wasn’t enough, one also has to contend with the flawless texture – spongy with no pores. Aah…the travails of “kasuteritis”! :oops:

Obviously, I am into my second stage of “kasuteritis” because I cannot seem to tire of that fluffy confection. I decided to combine kasutera with matcha this time…bwahaha! Now I combine the fear of a collapsing kasutera with the anxiety of how much matcha and mirin to add to the concoction. As if life wasn’t stressful enough!

I managed to replicate the spongy appeal but I did have a matcha and mirin deficit. Definitely double up on the two ingredients next time. The top was much smoother this time but it was not as brown as before…sigh! I did do away with the parchment paper and that stopped the shrinkage. Then I tried something else as well. Someone suggested refrigerating the cake to improve moistness and I read here that it is an essential step. Since I doubled the size of the cake this time compared to the last one, I was able to have my cake and still eat it…hehehe! I cut a portion for instant gratification and kept the other nicely wrapped in the refrigerator overnight. I am happy to report that it was indeed more moist!

Please note that I have doubled the matcha and mirin in the recipe below. I only used one tablespoon of each in the cake I made.

Matcha Kasutera (Green Tea Castella)

Prep Time: 10 minutes

Cook Time: 50 minutes

Yield: 1 8in x 8in cake

Matcha Kasutera (Green Tea Castella)


  • ¾ cup (115g) bread flour
  • 2 tbsp (10g) matcha (green tea powder)
  • 5 egg whites at room temperature
  • 5 egg yolks at room temperature
  • 2/3 cup (150g) sugar
  • 2 tbsp mirin


Line an 8 in x 8in (20cm x 20cm) cake pan with aluminum foil. Sieve bread flour and matcha together twice so that matcha is evenly mixed into the flour. 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 matcha mixture and beat until just combined. Add mirin and continue to beat for another minute.

Pour batter through a sieve into cake pan. Press with a spatula to help batter go through sieve. Tap pan on the counter to remove air bubbles. Using a spatula, smoothen the top of batter to remove any remaining bubbles.

Bake in preheated oven for 50 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 also be 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.


Please refer to Neapolitan Kasutera post for the updated list of ingredients.


If you are planning to use a wooden mold, do check out my dear friend’s blog Anncoo Journal who has also been bitten by the “kasutera bug”. :)

Enjoy…..and have a wonderful day! 8)