In a bowl, mix together the confectioner's sugar and the flour. Set aside.
Next, you must separate the egg whites from the yolks. You will need one and a half cups of egg whites and this always ends up being 12 large eggs for me. (Suggestion - crack each egg into a small cup, and then pour into a measuring cup. That way, if you do happen to break a yolk, you won't ruin the whole batch and have to start over. No egg yolks can be in the egg whites. Save the yolks for something else! I also have better results when I allow the egg whites to come to room temperature, but if you are crunched for time, don't sweat it!).
Pour the egg whites into a metal bowl (cannot be plastic) and set aside.
Dump in the cream of tartar, the vanilla extract, the maple extract and salt to the metal bowl of egg whites. Using an electric hand mixer, whip together until soft peaks begin to form - this usually take just a minute or two for me. I can never tell what a "soft peak" is supposed to look like, so I just keep going until it is thicker looking and kind of comes up with the beaters when I pull them out. (If you do not have an electric mixer, you can do this with a whisk. You will not need to go to the gym for any upper body training after this.).
Add the flour mixture a little at a time and mix with the electric mixer after each addition.
Add the sugar and mix well together with the electric mixer.
Pour it all into an ungreased tube cake pan.
Bake at 350 degrees for about 40 minutes. I tend to underbake mine just a little, since it will continue to brown slightly, after you remove it from the oven and allow it to cool.
I usually will run the end of a rubber spatula around the edge of the cake pan, after the cake has cooled slightly and has started to pull away from the sides of the pan. Dump it out onto a cake plate and try not to eat the entire thing while it is warm!