Kasutera

What is Kasutera?

Kasutera, which is also known as Castella, is a popular Japanese honey sponge cake. It was first introduced to Nagasaki by Portuguese traders in the 16th century.

Bread flour, eggs, sugar, and honey are the four essential ingredients in Kasutera. The sponge cake is beautifully contrasted by dark brown top and bottom crusts with a creamy yellow center. This delicate cake is soft, smooth, and bouncy, with just enough sweetness and a honey scent. The texture of Japanese honey sponge cake differs from that of typical western sponge cake in that it is more delicate and bouncy. It is entirely supported by egg foam. There is no butter, oil, or leavening ingredient such as salt or baking powder in this recipe. It also achieves the same by using bread flour that has a greater gluten concentration rather than normal flour.

Ingredients

• 6 large eggs (50 g each without the shell) 
• 1 cup sugar
• 1 ⅔ cup bread flour 
• ⅓ cup honey
• 2 ½ tbsp water

Honey Mixture to Brush Kasutera

• 1 tbsp honey
• ½ tbsp water 

Steps:

1. Gather all the ingredients and preheat the oven to 320ºF (160ºC). If it is a convection oven, then reduce temperature by 25ºF (15ºC). Cut parchment paper to fit the baking pans.
2. Sift the bread flour twice. 
3. Add 2 ½ tbsp warm water to honey. Whisk well.
4. Crack eggs into the bowl and vigorously whisk until combined and add sugar to it.
5. Beat the eggs and sugar on high speed. The volume of the beaten eggs will increase about 4 times. The texture will be thick and the color will be pale yellow. When you stop the mixer and lift the whisk attachment, the mixture should fall in ribbons.
6. Add the honey mixture into the egg mixture and whisk it at low speed (Speed 2) until combined, about 30 seconds.
7. Add the bread flour at three separate times. Do not overmix.
8. Spray the pans with oil and spread out evenly with a pastry brush.
9. Put the parchment paper in the pans and make sure the paper sticks to the pans. Add oil and spread out evenly with a brush if it does not stick.
10. Pour the batter into the pans. Then using a skewer, draw a zigzag line to remove the air bubbles in the batter. Tap the pan several times to release air bubbles.. 
11. Bake at 320ºF (160ºC) in the middle rack of the oven for 35 to 40 minutes or until it's golden brown.  A skewer inserted in the center will come out clean. When done, the cake sides will pull away from the pan slightly; the top will be flat and feel spongy when pressed with a finger.
12. Mix 1 tbsp honey and ½ tbsp warm water in a bowl and apply this mixture on top of the cake with a pastry brush.
13. Place a sheet of plastic wrap on the counter top. Take out the cake from the pan to the plastic wrap, top facing down and gently peel off parchment paper. Wrap the cake with plastic wrap immediately to keep the moisture and while it's hot store in the refrigerator overnight (at least 12 hours), keeping the top side facing down. 
14. Once you take out the cake, wait till the cake comes to room temperature and then slice off the sides of the cake with a sharp bread knife and cut into ¾ to 1 inch thick slices. 

And it's ready to be served.

You can also enjoy this with tea or coffee. 

Note:

1. Eggs should be at room temperature.
2. Kasutera gets an elastic bouncy texture from bread flour, and all-purpose flour cannot achieve this texture.
3. Water should be warm.
4. Fill the pans only until it's 80% full.

Why does my Kasutera deflate?

Under whisked meringue is not stable and it can cause a collapse. Over whisked meringue will make the cake very dense so getting the right texture of the meringue is critical to the success of the Kasutera.

How do you keep a Kasutera from sinking?

Cool these cakes upside down. By cooling the cake upside down, the cake has enough space to stretch out of the pan, rather than collapsing into the bottom of the pan.

Use Bread Flour

Why does a hard and dense layer form at the bottom of the cake although the top layer turned out beautifully?

For the cake to rise, there must be enough air beaten into the mixture. Make sure to beat the eggs for the proper amount of time. It will have a thick texture and a pale yellow tint. The mixture should fall in ribbons when you stop the mixer and lift the whisk attachment. Sift the flour twice to loosen it.

 Let us know about your experience in the comment section below.