Tapioca flour. Egg yolk. Egg white. Sugar.
Beat the egg whites in a bowl until foamy.
Add sugar and continue whipping.
Add egg yolks and vanilla extract and mix.
Sift in cake flour and gently combine.
Spread the batter thinly on a baking tray.
Bake for 15 minutes in a preheated oven at 180°C (356°F).
Let it cool, then cut into desired pieces.