Preheat your oven to 350 degrees F (175 degrees C). Do not grease your 10-inch tube pan (Angel Food Cake Pan).
In a large, clean bowl, combine the egg whites and cream of tartar. Beat with an electric mixer on medium speed until soft peaks form.
Gradually add 1 cup of the superfine sugar, one tablespoon at a time, while beating on high speed. Continue beating until stiff, glossy peaks form and the meringue holds its shape.
Beat in the vanilla and almond extracts.
In a separate bowl, whisk together the remaining 1/2 cup of superfine sugar, the sifted cake flour, and salt.
Gently fold the flour mixture into the meringue in three additions. Use a rubber spatula and cut down through the center, then sweep up the side of the bowl. Do not overmix; stop folding just when no streaks of flour remain.
Carefully pour the batter into the ungreased tube pan. Run a thin knife through the batter to release any large air pockets.
Bake for 35 to 40 minutes, or until the top springs back lightly when touched.
Immediately invert the pan onto its feet (or over the neck of a bottle if your pan does not have feet). Cool completely upside down, about 1.5 to 2 hours.
Once completely cool, run a thin knife around the edges and the center tube to release the cake. Serve immediately or store at room temperature.
Notes
Use room temperature egg whites for the best volume when whipping.
Sift the cake flour twice before measuring to ensure maximum lightness.
Cooling the cake upside down prevents the delicate structure from collapsing.
Serve topped with fresh berries and a light dusting of powdered sugar or whipped cream.