Preheat the oven to 325ºF.
Add the sugar to your blender carafe or food processor bowl. Pulse about 20 times, or until the sugar is powdery. Let it rest in the blender or bowl until the powder settles down.
Use a spoon to transfer 1 cup of the sugar to a measuring cup and set it aside.
To the sugar remaining in the blender or food processor, add the cake flour and salt. Pulse 10 times to combine and aerate the mixture. Set this aside.
Add the room temperature egg whites and the cream of tartar to the work bowl of a stand mixer fitted with a whisk attachment. If you do not have a stand mixer, you can use a large mixing bowl with a hand mixer.
Beat the eggs on medium low until they’re foamy. With the mixer running, slowly add the reserved sugar completely then raise the speed to medium high. Beat until the egg white mixture reaches soft peaks.
When you lift the whisk from the egg whites, it should raise up a little mountain of egg white that slumps over at the top and slowly sinks down. This is the soft peaks stage.
Add the vanilla and almond extracts and whisk in just until incorporated.
Position a fine mesh sieve over the top of the bowl or use a sifter and sift about ⅓ of the flour mixture over the top. Fold in gently using a silicone spatula.
Repeat this twice more, folding just until the flour is combined. Spoon this into your ungreased tube pan. Gently shake the pan side to side to help smooth out the surface of the cake batter.
It does not need to be perfectly smooth, just mostly even.
Bake for 40 to 45 minutes, or until the cake is lofty and golden brown and a toothpick inserted near the center of the cake comes out clean.
Invert the tube pan over a cooling rack or a glass soda bottle and let the cake cool completely; about 3 hours. If cooled upright, the cake will collapse under its own weight. Cooling upside down keeps it lofty and airy and delicate!
When the cake is cool, run a thin, flexible spatula or butter knife around the edge of the cake and turn it out onto a serving plate.
Use a serrated knife like a bread knife to cut the cake. It is too delicate to hold up to being cut by a chef’s knife or butter knife; that will just crush it.
This cake will store well, wrapped thoroughly but gently, in the refrigerator for up to a week.
Serve with a dusting of powdered sugar, berries tossed in granulated sugar, your favourite jam, a dollop of lemon or lime curd, or any combination of those!