This cake is so good that it’s hard to stop eating. The process of making the Japanese cotton sponge cake is similar to most sponge cake recipes. The recommended temperature and baking time is one of the most unreliable measurements in any recipe for cakes. Most of the ovens do not have a very accurate temperature indicator.
The heat distribution and the size of the oven are other factors that affect the final result. Start by greasing a baking pan then line with parchment paper. Preheat the oven to 150°C/300°F. Combine butter and evaporated milk, and heat up over medium-low heat until the butter has melted. Sift in cake flour, and mix until combined.
Combine 1 egg and egg yolks, add to batter gradually, and mix until smooth. In a clean mixing bowl, whisk egg whites on low speed until foamy. Add in salt and lemon juice, and whisk until small bubbles are formed. Add in sugar gradually, and whisk on low speed until soft peak. Add meringue to egg yolk batter in 3 batches, and mix gently with a hand whisk.
Fold gently until well mixed with a spatula. Tap mixing bowl a few times on countertop to burst large bubbles. Pour the batter into a lined baking pan, and tap a few times to break large bubbles. Put a baking pan with batter into a larger pan, then fill the larger pan with plain water, about 1″ high, for a water bath. Bake at 150°C/300°F for 1 hour 50 minutes, until fully cooked. If your cake does shrink when out of the oven, then your oven temperature is too hot.
Try reducing the baking temperature to 140°C. The cake should rise slowly during baking to prevent it from over-rising and then collapsing when out of the oven. Unmould the cake and cool completely on a wire rack. Cut into pieces with a serrated knife when completely cooled.
- 60g butter, melted
- 80g flour, sifted
- 80ml full cream milk
- 1 whole egg
- 5 egg yolks
- 5 egg whites
- 120g caster sugar
- Line a baking pan and set aside.
- Melt butter ( you can use a microwave) and pour it into a mixing bowl.
- Add sifted flour and use a spatula to mix the flour and butter until well blended.
- Add milk and continue to mix.
- Add egg yolks, one by one, mixing as you go along, followed by the whole egg. Set aside.
- Using a handheld mixer, beat egg whites until foamy and add sugar.
- Continue to beat until stiff peaks.
- Pour the egg yolk mixture into the egg whites and fold to mix until you do not see any streaks.
- Pour batter into the lined pan and bake at 150°C for 1 hour and 50 minutes on the middle rack until a skewer inserted into the center of the cake comes out clean.
- Remove the cake from the oven immediately and drop it from a height (about 12 inches ) onto your tabletop.
- Unmould the cake and leave it to cool completely before serving.