Place an oven rack in the second lowest position and preheat the oven to 325F. Line the bottom with parchment paper (see recipe notes). Do not grease the pan.
In a medium bowl, whisk together the granular and powdered sweeteners.
In a large bowl, whisk together the almond flour, protein powder, half the sweetener mixture, and the salt. Use a sieve or strainer to sift the flour mixture into another large bowl. Do this back and forth between the bowls 3 times.
If you do not have a sieve, simply use a fork to fluff up the mixture for several minutes, to break up clumps and make it lighter and airier.
In another large bowl, beat the egg whites with the cream of tartar until frothy. With the beaters running, slowly add the remaining sweetener until the whites hold medium peaks (the tips should flop over slightly when the beaters are lifted).
Add the extracts and continue to beat until the whites hold stiff peaks (tips should stand up straight when beaters are lifted).
In four separate additions, carefully fold the flour mixture into the egg whites until well combined (a large silicone spatula works best for this). Be sure to scrape the bottom of the bowl well to mix in any ingredients that may have settled there.
Spread the batter in the prepared pan and smooth the top. Wipe off any drops of batter from the sides, and lightly tap the pan on the counter a few times to release any air bubbles.
Bake for 40 to 50 minutes, rotating the pan halfway through baking, until the top is uniformly golden and springs back when lightly pressed.
Remove and let cool in the pan 20 minutes, then turn the pan upside down and let cool completely.
Run a sharp knife around the inside of the pan, and around the tube in the center, to loosen the cake. If the pan has a removable bottom, you can simply push up to release the cake. Otherwise, invert the pan over a cake plate and tap the bottom to release the cake.
To line the cake pan, you will need a 9-inch circle of parchment paper. Fold the paper in half and then in half again to create a cone. Cut enough out of the tip so that when it is opened, it fits over the center of the tube pan. It does not need to be perfect.