Beat the egg whites until foamy. Add in the sugar gradually and whisk until soft peak forms.
Preheat the oven to 180°C (350°F) for 10 minutes.
Fold the meringue into the yolk mixture in three separate additions. Gently mix each addition until no streaks remain.
Pour the batter into the prepared cake pan. Tap the pan lightly on a tabletop to get rid of any trapped air bubbles in the batter.
Wrap the cake pan with aluminum foil. Make sure that the sides of the pan are fully covered by foil to prevent water from going into the pan.
Place the cake pan into a baking pan. Add about an inch of hot water to the baking pan, so it surrounds the pan. Make sure you add enough water, so it does not fully evaporate during the baking process.
Bake the cake for 10 minutes at 170°C (325°F) for 10 minutes. Then reduce the heat to 150°C (300°F) for another 45 minutes.
Once it is done, turn off the oven and let the cake be in the oven for 5 minutes.
Remove from the oven and from the pan. Let cool completely on a wire rack. Chill in a fridge for approximately 4 hours. Ready to serve.