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Japanese sponge cake – How to make the most cottony and bouncy cake

Finally, I am getting everything right on how to make the Japanese sponge cake after many attempts.

The cake is bouncy like a sponge, with the soft and delicate texture resemble cotton when you tear it apart.

I also add the cake batter to the dough of the chocolate Japanese milk bread. Here is the result- my delectable bread-cake that I missed so much after the nearby bakery decided to stop producing it.

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How to make Japanese sponge cake in twenty minutes

This article is all about how to make the Japanese sponge cake. Please refer to this article to find out how to make the Japanese milk buns that are incredibly soft.

The process of making the Japanese cotton sponge cake is similar to most of the sponge cake recipes. Nevertheless, there are some fine details which I will explain in detail in the following sections.

1. Measure the flour and butter correctly

The importance of sieving the flour

Measure 100g of plain flour and sieve at least once. What I mean by plain flour is any wheat flour that is label as cake flour or all-purpose flour. The percentage of gluten in these type of flours is relatively low, about eight to ten percent, which is ideal for making sponge cakes.

I sieve the flour not because it is dirty. The flour that I get locally are very clean, but I want to ensure that it is free from any lumps and large particles. The fineness of the flour is critical to get the cottony texture. If you happen to get any superfine cake flour, go for it. It will significantly improve the texture of the cake. Since I have not been able to purchase it this time, I have to sieve the flour to make sure the cake will turn out well.

Use melted butter to mix with the flour

Place 75g of unsalted butter in a pan/pot over low heat until it melts. You can melt the butter in the microwave oven by using low heat for a minute. Keep an eye to the butter and do not brown it as it will alter the flavor and smell of the butter.

You may want to substitute the melted butter with corn oil. However, a sponge cake made with good quality butter has a better flavor.

Add the flour to the melted butter after it is cooled. We do not want to add the flour to the hot butter to avoid the flour being cooked at this time. We are not here to make choux pastry!

Do not worry if the flour and the butter forms a sticky mass at this point of time. It will turn into a smooth batter after adding milk and the egg yolks subsequently.

Note: This is not a gluten-free formula. I have not tried to make a sponge cake with any gluten-free recipe so far.

2. Add the milk

Add 60ml (4 tablespoons) of milk to the flour-butter mixture. You may pour all the milk into the mixture or add in batches. It will not make any difference to the result.

The milk will dilute the flour-butter mixture to form a thick paste.

3. Separate the egg yokes from the egg whites carefully

We need to add the egg yolks to the above flour-butter-milk paste to form the batter.

So far the process is relatively straight forward. There is quite easy and does not involve much technique. However, please pay attention when you separate the egg yolks from the white. It can be the make or break step for this recipe.

Do not even let a trace of egg yolks contaminate the egg whites. We need pure egg whites to prepare meringue, and it has to be free from oil to be successful. Egg yolks are oily, and that is why it has to be very careful not to break the yolks.

Here are my recommended steps:

  • Use a clean stainless steel bowl to keep the egg whites. Wipe the bowl with paper towels to make sure that it is free of oil. The bowl must be large enough as we will use it to beat up the egg whites to form the meringue.
  • Use the egg yolk separator to remove the egg white from the yolk. I always crack the egg in a separate bowl to make sure any broken eggs will not contaminate the bulk of the whites.
  • It is not possible to separate all the whites from the yolks. However, there should not be even a trace of yolk in the white as it will hinder the expansion while making the meringue.

4. Making the batter

Lightly beat the egg yolks and add to the flour-butter-milk mixture.  Again I have tried to add the egg yolks in batches to the mixture, but it makes no difference compare to pouring all the yolks at one go.

The egg yolks will dilute the paste further into a batter. It is at this time that you need to mix it thoroughly. I mean to mix it, not to beat it as beating will create bubbles that are not a welcome inclusion to the cotton-like texture.

Mix it in one direction until it is free from any visible lumps. The final batter should have a very smooth texture.

Once you have done that, you have won half of the battle. Let’s move on to prepare the meringue.

5. Beat the egg whites until it forms stiff peaks

The egg white should be at room temperature while making the meringue. Remove the eggs from the refrigerator and wait for it to return to the room temperature before cracking them.

Beat the egg whites with a hand-held mixer at low speed. If the room temperature is too low during winter, place the bowl of egg whites on a hot water bath. Warm egg whites can trap more air in its structure and expand its volume rapidly during the beating process.

  • Add 80g of castor sugar or fine sugar into the egg white after fifteen seconds of beating.
  • Continue beating the egg whites until the volume triple. The egg white will change gradually from transparent to pure white, and become thicker.
  • Eventually, the egg whites become so thick that when you switch off the electric beater and turn it upside down, the egg white that sticks onto the beater blade will become so stiff that it will firmly stand without drooping. Beat the egg whites until it can form a stiff peak.

Nevertheless, some bakers prefer to beat the egg whites to form a soft peak, which means that the peak will droop a little when you overturn the beater blade.

How to maintain the best volume for the meringue

If the meringue forms only until the stage of the soft peak, it will lose volume rather quickly while you start to fold since it is less stable. In contrary, meringue that forms stiff peak stage is firmer and need more folding until it can incorporate uniformly with the batter. The longer you fold, the batter will deflate more.

My preference is first to beat it until it forms a soft peak, then beat further by stopping every twenty seconds to check if it achieves the stage of stiff peak. I do not want to overbeat it because the meringue is hard to combine with the batter once it becomes too stiff.

I will dilute the batter with a quarter of the meringue so that it is easier to mix, then add the diluted batter back to the bulk of the meringue. Fold the meringue into the batter slowly until it is almost homogenous.

The batter will deflate beyond the optimum level if you fold the meringue until the batter is homogenous.

Then I will pour the cake mix into the cake pan. The pouring action will finish up the last bit of mixing which will eventually produce a homogenous cake mix in the pan.

Japanese sponge cake is bouncy like a piece of sponge, with the soft and delicate texture resemble cotton when you tear it open. This articles will show you every detail of how to make Japanese cotton sponge cake. (with video).

6. Line the cake pan with baking paper

Line the cake pan with a large piece of baking paper enough to cover the sides of the square cake pan. Brush the paper with some melted butter.

Since I am using a cake pan with a detachable base, I have to wrap the exterior of the pan with aluminum foil to avoid the water from the water bath from seeping into the pan.

After pouring the cake mix into the pan, you will notice there will be some bubbles on the surface. These bubbles will create little craters on the surface if you do not get rid of them. You can do this by:

  • Gently tap the cake pan a few times to break the large bubbles.
  • Use a bamboo skewer or toothpick to break the smaller bubbles.

7. Baking at the right temperature

Place the cake in the hot water bath. Once the oven is heated, bake at 150°C/300°F for sixty minutes.

But it may not be right sometimes!

The recommended temperature and baking time is one of the most unreliable measurements in any recipes for cakes. Most of the ovens do not have a very accurate temperature indicator. The heat distribution and the size of the oven is another factor that affects the final result.

My suggestion is to take a quick look at the cake after baking for forty minutes. If the cake has already expanded, then it should be fine. Otherwise, increase the temperature by 10°C to make sure the air trapped in the batter expands and push up the cake.

When the cake is nearly done, you can open the oven door more often without worrying the sudden drop of temperature will cause the cake to deflate. Check the color of the cake. The actual baking time will depend on the color of the cake. You need to check. It is not possible to set the temperature precisely each time unless the oven has a digital control panel.

8. Do not cut the cake immediately after baking

Remove the cake from the oven and water bath and let it cools on the table for fifteen minutes. The cake will shrink a little and detached from the sides of the pan.

Overturn it onto a wire rack and remove the paper. Then, place a cake board on it and revert the cake again. Now you have Japanese sponge cake ready to cut and serve.

Additional information – May 2020

I have just revisited this recipe as some of the readers were unable to produce the same result as mine while following the recipe diligently. There are two commonly happened problems that I want to address.
– The cake is undercooked at the bottom
– The cake is dense

1. Why is the sponge cake undercooked at the bottom? 
The cake is baked in a water bath. The purpose of the water bath is to provide a slow and even heat, protecting the delicate sponge texture. The cake will rise slowly and evenly with no rapid expansion, and therefore achieve a smooth and cottony texture. 

However, the water at the lower part of the cake brings down the temperature, causing the upper part to expand faster than the lower part, resulting in the bottom becomes denser than the top.

To solve this problem, I have made two adjustments:
– First, increase the temperature to 160 °C/320°F.
– Put the cake on the lowest rack of the oven. The bottom of the cake will heat up efficiently now and rise at the same speed as the top, and will not cause the formation of a dense layer. 

The water bath will still function to ensure sufficient moisture in the oven, forming a flat top surface without crack, and moist texture. 

The lowest rack of my oven is just one inch above the bottom heating element. You may need even higher than 160°C if it is further away from the heating element. You have to forgo the water bath if it still doesn’t work. There are no two ovens that behave the same. The cake will become dryer without a water bath, though.

The most common reason when the sponge cake is still uncooked after baking one hour is due to low temperature. The distance between the baking rack and the heating element makes all the difference. You know your oven best!

2. Why is my sponge cake denser than what is shown in this post? 
In my opinion, the main reason is overmixing while folding in the meringue. If I mix until the meringue is disappeared, the cake will deflate too much, resulting in a dense texture. 

It is better to fold in the meringue gently and stop when there are still traces of meringue scattered randomly in the batter. Pouring the batter into the cake pan slowly from a high position will give the batter a final mix naturally. 

Also, the meringue should be beaten until you can make a stiff peak when leaving up your spatula. Otherwise, it will collapse rapidly during mixing and folding and resulting in a dense cake.

Take a look at the two images below. 

Image 1: The cake on the right has a dense layer at the bottom. It is baked on the middle rack. The cake on the left, which is perfect, is baked on the lowest rack.
Image 2: The volume of the cake on the left is less. It is the result of folding the meringue until it disappears thoroughly. On the contrary, the folding of meringue for the cake on the right stop short when there are still traces of meringue visible. Hence, it has a better volume.

Variation: How to make Japanese sponge “cake-bread”

I also combine this recipe with the Japanese milk bread published in this blog to create a cake-bread loaf. You can refer to the bread recipe article to make the bread. I have added a teaspoon of cocoa powder to change the bread to a chocolate color.

To do this. Place a small dough of the bread into a loaf pan. Pour the sponge cake mix on the dough after it doubles in size. Bake as the same temperature and duration in the sponge cake recipe. 

Yield: 1 cake cut to 9 portions

Japanese Sponge Cake

Japanese sponge cake is bouncy like a piece of sponge, with the soft and delicate texture resemble cotton when you tear it open. This articles will show you every detail of how to make Japanese cotton sponge cake. (with video).

Japanese sponge cake is bouncy like a piece of sponge, with the soft and delicate texture resemble cotton when you tear it open.

Prep Time 20 minutes
Cook Time 1 hour
Total Time 1 hour 20 minutes


  • 100g (3.5 oz) cake flour
  • 75g (2.6 oz) melted butter
  • 60ml (4 tbsps) milk
  • Vanilla extract (optional)
  • 6 large eggs
  • 80g (2.8 oz) castor sugar


  1. Measure the plain flour and sieve a least once. 
  2. Add the flour to the melted butter after the butter is cooled. Mixed well.
  3. Add the milk. Mix well.
  4. Lightly beat the egg yolks and add to the flour-butter-milk mixture. Mix it thoroughly. 
  5. Beat the egg whites with a hand-held mixer at low speed. 
  6. Add the sugar into the egg white after about fifteen seconds of beating.
  7. Continue beating the egg whites until it can form a stiff peak.
  8. Add a quarter of the meringue to the batter to dilute the batter so that it is easier to mix, then add the diluted batter back to the bulk of the meringue. Fold the meringue into the batter slowly until it is almost homogenous. 
  9. Line the cake pan with a large piece of baking paper. Brush the paper with some melted butter.
  10. Pour the cake mix into the pan.
  11. Gently tap the cake pan a few times to break the large bubbles.
  12. Place the cake on the lowest rack, with the hot water bath. Bake at 160 °C/320°F for sixty minutes.


If you encounter any audio / visual problem of viewing this video, you can view it from YouTube by clicking this link, which will open in a new tab.

Nutrition Information:



Serving Size:

1 cake cut to 9 portions

Amount Per Serving: Calories: 187Total Fat: 10gSaturated Fat: 5gTrans Fat: 0gUnsaturated Fat: 4gCholesterol: 142mgSodium: 105mgCarbohydrates: 18gFiber: 0gSugar: 9gProtein: 5g


Saturday 25th of June 2022

how big of a pan should i use?

KP Kwan

Wednesday 29th of June 2022

I use an 8-inch square pan for this recipe.


Monday 15th of November 2021

Good day! Awesome recipe! I have tried replicating this but I still end up with the same result - a failure. The eggs seem to settle down at the bottom of the pan while baking. The end result tastes like an egg pie. I have already tried putting the rack on the lowest layer and increasing the temperature to 160 degrees. I am using a gas oven by the way.

Do you have any tips regarding this? Thank you very much!

KP Kwan

Saturday 20th of November 2021

I do not have a definite solution to your problem and would appreciate any expert who read this could provide an answer. The following are steps I will try, and hopefully, it works :) - Reduce the amount of water in the bath. That may help to let the bottom part heat up faster and expand. The bath produces moisture in the oven to rise slowly and get a flat surface. Other than that, it does not serve other purposes IMO. - Up the temperature to 170°C, as I think it is still not exceedingly high.


Thursday 15th of July 2021

Hello! Unfortunately, I do not have cake flour. Will the light texture be completely ruined if I use all-purpose?

KP Kwan

Thursday 15th of July 2021

The content of all-purpose flour is close to cake flour. Therefore, there will not be any big difference in the texture.


Thursday 10th of June 2021

If I want more of a chocolate sponge can I just add a little cocoa powder with the flour to this recipe? Will it impact other ingredients or can I simply just add it?

KP Kwan

Thursday 10th of June 2021

I have not tried this way so far, but a small amount should not affect the cake's texture. However, if you want to add a large amount, you need to test the formula as the cocoa powder is heavy.


Tuesday 8th of June 2021

Thank you for the recipe! I found the steps and advice easy to replicate, and ended up with a yummy and soft sponge that was perfect for strawberry shortcake. However, I did have an issue with guessing the size of baking pan to use. The first time, I tried using a 9" springform pan and it ended up a bit thinner than I wanted (I wanted to slice it into two layers). I made it again using a 7.5" springform and it ended up at a better height. Also: IT DOES NOT REFRIGERATE WELL AT ALL!! I made the cake Saturday afternoon, stored it in an air-tight container at room temp overnight, but refrigerated it Sunday evening evening because my mother suggested it would keep better. Terrible idea! I tried having some on Monday and found it became super dense, gummy, and had a VERY unpleasant taste (not even a stale taste - it was almost sulfur-y and bitter/astringent). I've never had such an issue with any other cakes I've made, so I have to wonder if it's due to the amount of egg in it? I baked the cake to an internal temperature of 180 degrees fahrenheit/82 degrees celsius (the point at which the top was quite golden), so the eggs should have been 100% cooked... but it almost tastes like how I imagine rotten eggs. It was very strange, and also very sad since I was looking forward to having more with the leftover strawberries I had :( I would use the recipe again in the future, but now I know it has to been eaten as soon as possible!!


Thursday 10th of June 2021

Update: Apparently the cake that I assembled as a strawberry shortcake and left at my friend's house was still fine the next day, so I'm not sure what happened to our particular sponge. I did leave the parchment paper on the bottom, so it's possible that it became gross (maybe moldy) over time and affected the cake. Another possibility is that the tupperware I stored it in was not washed properly prior and I didn't notice? It's still a big mystery, but it seems less to do with the recipe now! My dad was upset that I didn't save him a slice, so I'll probably be making it again soon and we'll see how it keeps this time around.

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