Yoghurt cloud cake: the softest cake ever!

1. Separate the egg yolk from the white.
2. Mix the grated lemon peel, the yoghurt and the sifted flour with the egg yolks and mix well with a whisk.
3. Add the lemon juice to the egg whites (room temperature) and start beating. As soon as foam forms on the surface, add 1/3 of the sugar and continue beating the sugar three times. You must obtain a smooth and whipped mixture.
4. Add the egg whites to the yolk mixture three times and stir gently from bottom to top.
5. Pour the mixture into the 16cm baking tin lined with baking paper.
6. Place the cake pan in a slightly larger shape, then place it in a baking tray and add water to create steam as it cooks.
7. Cook at 110°C/230°F for 50 minutes and at 170°C/338°F for 10 minutes. Finally, let the cake rest in the switched off oven for 10 minutes.
8. Let it cool in the fridge, sprinkle with powdered sugar and enjoy the cold cake!