Preheat your oven to 350°F and prepare a 9-inch cake pan with parchment paper (no need for butter).
In separate bowls, carefully separate the egg whites and yolks.
In the bowl with the egg yolks, add half of the sugar, salt, and vanilla extract. Whisk until light and fluffy.
Stir in the milk.
Sift in the flour, cornstarch, and baking powder. Gently mix until combined.
In another clean bowl, whisk the egg whites with cream of tartar until stiff peaks form. Gradually add the remaining sugar while whisking.
Gently fold the egg whites into the cake batter in 2-3 additions.
Pour the batter into the prepared pan and bake for 15-18 minutes until a toothpick comes out clean.
Let the cake cool in the pan.