Preheat the oven to 350°F (177°C). Line bottom of two 8 or 7-inch cake pans with parchment paper. No need to grease the pan.
Separate egg whites and yolks, making sure not even a little bit of egg yolk gets into the whites. (TIP: It's easier to separate the egg when they're cold right out of the fridge.)
In a mixing bowl with whisk attachment, whisk together egg yolks and ½ cup of sugar until pale and tripled in volume, about 5 minutes.
Meanwhile, sift flour and salt.
In another mixing bowl with whisk attachment, beat egg whites at medium low speed until foamy.
Add remaining ½ cup of sugar 1 tablespoon at a time and continue to whisk until stiff peaks, gradually increasing the speed to medium high, 7-10 minutes.
Using a spatula, add 1/3 of the whipped egg whites into the egg yolk mixture and gently fold until mostly smooth. Add the remaining egg whites and gently fold until smooth.
Add sifted flour into the batter in 3 stages, whisking the batter well after each addition.
Pour the batter into prepared pan and smooth the top.
Bake the cake until inserted toothpick comes out clean, 25-30 minutes. Don’t open the oven for at least the first 30 minutes!
Let the cake cool for 5 minutes in the pan. Then run a knife around the edges and invert onto a cooling rack. Cool completely. Once cooled, wrap with plastic wrap and refrigerate for 1-2 hours, or preferably overnight. It’ll be easier to cut it when the cake is thoroughly chilled.