Grate the lemon zest on a fine grater (you can take a dry one).
Turn on the oven to preheat. Set the temperature to 180 degrees. Separate the whites from the yolks.
Mix the yolks with sugar (set aside 3 tablespoons of sugar for proteins) and lemon zest. Beat everything thoroughly.
Sift the starch into the yolks, without stopping stirring (whipping).
Beat the whites with three tablespoons of sugar until steep peaks.
Gently introduce the proteins into the dough, mixing in a circular motion “from bottom to top”.
If a split form is used, it does not need to be prepared. If it is ordinary, you need to cut out a circle of the desired dia from parchment paper and lay it on the bottom of the mold. Pour the dough into the mold.
Bake the biscuit at 180 degrees for 45 minutes. After turning off, cool in the oven. It is also recommended to cool the sponge cake upside down on a wire rack.