Adjust the oven rack to the lower middle position and preheat oven to 325°F (163°C).
Take 1 cup of the sugar and set aside.
Add the 3/4 cup of sugar, cake flour, and salt to a food processor and pulse 5-10 times until sugar/flour/salt mixture is aerated and light.
In a large bowl using a hand mixer or a stand mixer fitted with a whisk attachment, whip egg whites and cream of tartar together on medium-low until foamy, about 1 minute.
Switch to medium-high and slowly add the 1 cup of sugar you set aside.
Whip until soft peaks form, about 5-6 minutes.
Add the vanilla extract, then beat just until incorporated.
In 3 additions, slowly sift the flour mixture into the egg white mixture using a fine mesh strainer, gently folding with a rubber spatula after each addition. It's important not to add the flour mixture all at once! Adding it all at once will cause the whites to deflate.
Pour and spread batter into an UNGREASED 9 or 10 inch tube pan. Shimmy the pan on the counter to smooth down the surface.
Bake the cake until a toothpick inserted comes out clean, about 40-45 minutes. Rotating the pan halfway through baking. Remove from the oven, then cool the cake completely upside-down, about 3 hours. ****
Once cooled, run a thin knife around the edges and gently tap the pan on the counter until the cake releases.