Method:

1. Preparing the Ingredients:
– Preheat the oven to 175°C and prepare a bundt cake tin with a diameter of about 25 cm, buttering it and lightly flouring it.

2. Processing the Ingredients:
– In a large bowl, mix the egg yolks and sugar until the mixture is light and fluffy.

3. Adding the Other Ingredients:
– Add the natural yogurt and melted butter to the egg yolk and sugar mixture. Mix well to combine everything.

4. Adding the Dry Ingredients:
– Add the potato starch, flour and vanilla sugar, sifted together. Mix the dry ingredients well into the liquid mixture.

5. Preparing the Egg Whites:
– In another bowl, beat the egg whites until stiff with a pinch of salt.

6. Incorporating the Egg Whites:
– Add the beaten egg whites to the mixture, mixing gently from top to bottom so as not to deflate the egg whites too much. The dough should be smooth.

7. Baking:
– Pour the dough into the prepared pan, leveling the surface with a spatula.
– Bake in a preheated oven at 175°C for about 35-40 minutes, or until the cake is golden brown and a toothpick inserted into the center comes out clean.

8. Cooling and Serving:
– Once cooked, let the cake cool in the pan for a few minutes, then carefully turn it out onto a wire rack and let it cool completely before serving.

This yogurt cake is sure to be a hit thanks to its softness and the delicate flavor of yogurt. Happy baking and enjoy your meal!