Separate the egg whites and yolks, ensuring no yolk gets into the egg whites. Place the yolks in a clean mixing bowl.

Add 220g of thick yogurt to the yolks and whisk until smooth and well combined.

Sift 75g of cake flour and 15g of cornstarch into the yolk mixture. Whisk until the mixture is smooth and lump-free. Set aside.

Place the egg whites in a clean, dry bowl free of oil and water. Add 3 drops of lemon juice or white vinegar if using.

Begin whipping the egg whites with a hand mixer. Gradually add 40g of zero-calorie sugar in batches, starting at low speed and increasing to high speed.

Continue whipping until the egg whites reach a state between medium and stiff peaks (the meringue should form a slight curve when you lift the whisk).

Add 1/3 of the whipped egg whites to the yolk mixture. Gently fold with a spatula using a cutting and lifting motion to combine without deflating.

Transfer the mixture back to the remaining egg whites. Gently fold until fully incorporated, forming a smooth, airy cake batter.

Pour the batter into a cake mold. Lightly tap the mold on the counter to remove large air bubbles.

Preheat your oven to 145°C (293°F). Use the water bath method by placing a tray of water on the oven rack, then positioning the cake mold on the tray. To ensure no water seeps into the cake mold, place the mold inside a waterproof container or wrap it securely with aluminum foil.

Bake for 55 minutes.

Once done, remove the cake from the oven and let it cool at room temperature.

Once cooled, refrigerate for a few hours. Chilling enhances the texture and flavor. Slice and enjoy!