Separate 4 eggs into two bowls. To the bowl with the yolks, add Greek yogurt and vegetable oil and mix. Then add cake flour and starch, mix until smooth, and set aside.

In the bowl with the egg whites, add sugar and whip with an electric mixer until it becomes a glossy meringue with stiff peaks.

Gently fold the yolk batter into the meringue. Mix from the bottom up until just combined, being careful not to deflate the batter.

Pour the batter into a baking pan, smooth the top, and tap the pan on the counter to remove large air bubbles.

Place the pan in an air fryer preheated to 180°C. Add a bowl of water alongside it to create steam.

Bake at 170°C for 10 minutes, then lower the temperature to 130°C and bake for an additional 50 minutes.

Once baked, let the cake cool. Dust with powdered sugar before serving if desired.