Step 1: Preheat your oven to 350°F (175°C). Ensure you have a clean, ungreased 10-inch tube pan ready.
Step 2: Sift the cake flour, cornstarch, and 1/2 cup of the sugar together three times into a medium bowl and set aside.
Step 3: In a large clean bowl or stand mixer, beat the egg whites until foamy. Add the cream of tartar, salt, and extracts.
Step 4: Continue beating on medium speed while adding the remaining 1 cup of sugar, one tablespoon at a time, until stiff, glossy peaks form.
Step 5: Gently fold in the flour mixture, about 1/4 cup at a time, using a spatula until just incorporated. Do not overmix.
Step 6: Spoon the batter into the tube pan and run a knife through the batter to remove air pockets. Bake for 35-45 minutes until the top springs back when touched.
Step 7: Immediately invert the pan onto a wire rack or bottle and let the cake cool completely (about 2 hours) before removing it from the pan.