Begin by mixing egg yolks, sugar, and vanilla extract.
Add the sifted cake flour to the mixture and set aside.
In a separate bowl, beat the egg whites until big foam starts to form. Gradually add 25g (1/4 cup) sugar, continuing to beat at medium-high speed until stiff peaks form.
Fold a third of the meringue mixture into the batter until fully combined. Then, add the rest of the meringue, folding carefully to avoid deflating the mixture.
Transfer to a baking pan and bake at 170°C (338°F) for 10 minutes.
Once cooled, cut into a circle the same size as the base of the silicone mold.