Sift flour, baking powder, and salt three times mix with sugar.
Separate the yolks.
Heat milk to room temperature.
Mix the yolks, milk, butter, lemon zest, and beat until foamy (beat for 7-10 minutes).
Add the dry ingredients mixture little by little. Stir with a spatula until smooth.
Turn on the oven and preheat it to 160-170 degrees. Mix whites and powdered sugar.
Whisk until firm peaks. Check – well-beaten proteins remain in the bowl even if you turn it over (just check carefully, if the squirrel is not completely beaten …)
Transfer a quarter of the protein portion to the dough. Gently, in a circular motion “from top to bottom” introduce the proteins into the dough.
Add the rest of the proteins. No less carefully introduce them into the dough in the same circular motions “from top to bottom”.
Transfer the dough to a mold with a diameter of 26 cm. The mold does not need to be lubricated.
Bake the chiffon sponge cake in the oven at 170 degrees for 35-40 minutes. The oven must not be opened during this time. Then check the biscuit for readiness. To do this, pierce the biscuit with a toothpick. If it remains dry, the biscuit is ready. If the dough is stuck on it, you need to cook the biscuit for another 5-10 minutes.
The finished chiffon biscuit can be turned upside down right in the shape so that it remains lush. Then put the form with the biscuit back in the turned-off oven and leave there until it cools completely.