Notes
Preheat your oven to 350°F. Grease a 9-inch round cake pan well and set it aside.
Beat the egg whites and cream of tartar on medium-high speed until soft peaks form. Add the remaining ¼ cup (50 g) sugar, and beat until glossy, stiff (but not dry) peaks form.
In a separate bowl, beat the egg yolks and ½ cup (100 g) sugar and vanilla on medium-high speed until pale yellow.
Gently fold half of the egg-white mixture into the egg yolk mixture until just combined, working carefully to knock out as little air as possible.
Sift the GF flour, cornflour and salt into the egg yolk/egg white mixture, again folding very carefully and gently until just combined.
Gently fold the remaining half of egg-white mixture into the batter.
Pour the batter into the prepared pan or pans and spread into an even layer.
Place in the center of the preheated oven and bake until the cake has begun to pull away from the sides of the pan and a toothpick comes out mostly clean, or with a few moist crumbs attached (about 35 minutes).
Allow the cake to cool in the pan for about 10 minutes before transferring to a wire rack to cool completely.
