Prepare all raw materials and utensils, and the plate containing protein must be water-free and oil-free.
Egg yolk and protein are separated. Take a plate to hold the egg yolk, pour water into it, sift in the low flour and 1/3 powdered sugar, and beat it evenly with a manual egg beater to make egg yolk paste.
Put the egg white on another plate, add the remaining 2/3 powdered sugar into the egg white three times, and beat the egg white into a good egg white paste with electric egg beater.
Pour the egg yolk paste into the egg white paste and stir it evenly from bottom to top with a silicone spatula.
Finally, pour the cake paste into a 6-inch round baking pan and gently shake out the air. Use a larger baking tray to hold water with a depth of 1/3, put the small baking tray into it, and put it into the preheated oven together, and bake at 150 for one hour.