Separate eggs while cold, and allow egg whites to come to room temperature, about 30 minutes (separating eggs is easier when the eggs are cold; but the egg whites need to be at room temperature to whip properly).
While the egg whites are coming to room temperature, in a large bowl, sift flour (either cake flour or all purpose flour + cornstarch) and powdered sugar together, 5 times.* Set aside.
Preheat oven to 350 degrees.
With a hand mixer or standing mixer on medium speed, whip egg whites, vanilla extract, almond extract (if using), salt and cream of tartar until soft peaks form.
Gradually add granulated sugar, about 2 Tbsp at a time, beating on high, until stiff peaks form (see picture above for stiff peaks).
Gently fold flour mixture, about 1/2 cup at a time, into the egg white mixture, until combined.
Spoon batter into an un-greased 10 inch tube pan gently (the pan must be un-greased).
Cut through the batter with a knife, as this removes any air pockets.
Bake for 35-40 minutes, or until the top of the cake is lightly golden brown and any of the cracks in the top of the cake look dry.
Immediately invert the pan upside-down, allowing it to cool for about 1 hour. (I inverted mine and rested it on a heat proof bottle.) Once cooled, use a knife to loosen the sides of the cake and invert cake onto a plate/serving dish (it might take a couple gentle shakes and taps to get the cake to come out of the pan).
Cut cake and serve with whipped cream and fresh berries.
Cake can be stored at room temperature for a couple of days; any longer and the cake should be stored in the fridge.
Enjoy!