Preheat your oven to 350°F (175°C) and position the rack in the middle. Sift the cake flour and half of the sugar together into a bowl to combine thoroughly.
In a clean, large mixing bowl, beat the egg whites on medium speed until frothy, then add the cream of tartar. Continue beating until soft peaks form, which means the egg whites will hold a gentle, curved shape when you lift the beaters.
Gradually add the remaining sugar a few tablespoons at a time while beating the egg whites, until stiff, glossy peaks form. The mixture should be thick and hold a firm peak when you lift the beaters.
Sprinkle the sifted flour mixture over the whipped egg whites in three parts. Gently fold each addition in with a spatula, using a soft, sweeping motion to avoid deflating the meringue.
Once fully combined, gently fold in the vanilla extract. The batter should be smooth and airy, with a delicate flow when lifted.
Pour the batter into an ungreased tube pan or angel food cake pan, smoothing the top gently with a spatula. Do not tap or shake the pan to settle the batter, as this can deflate the air bubbles.
Bake the cake in the preheated oven for about 35 minutes, until the top is golden and a toothpick inserted into the center comes out clean. You should see a crack forming and the cake expanding to fill the pan.
Remove the cake from the oven and invert the pan onto a cooling rack. Let it cool completely upside down to prevent collapsing and to help maintain its tall, fluffy shape.
Once cooled, gently run a knife around the edges of the pan to loosen the cake, then carefully remove it. It should be light, airy, and with a slight crackle on top.
Slice and serve the angel food cake plain, or with fresh fruit or whipped cream for extra flavor and presentation. Enjoy the tender, cloud-like texture with each bite!
