Preheat your oven to 325 F.
If you have a warm function on your oven, set your bowl of egg whites on it to warm them to 110 F (for faster soft peaks)
Whip egg whites for about 30 seconds on high speed.
Add cream of tartar and sugar. I also added my salt here.
Whip until soft, white peaks on highest speed with wire whips. This means it should come up when you remove the whisk from the bowl, but then flop over like the crest of a wave. If it points up but does not flop over, you whipped too long. That's ok - keep going.
On the LOWEST setting, incorporate the remaining dry ingredients just until mostly combined. Only a few short seconds. Optionally, do this by hand by using a spatula and folding down, around and up very gently.
Gently use your spatula to spoon the mixture into your pan. Smooth it out without pressing down.
Bake for approximately 20 minutes, until the middle is 210 F.
Let cool a few minutes before releasing the sides from the pan.
Turn it over, and slowly remove the parchment paper.
Slice gently with a bread knife. Excellent topped with fresh fruit and whipped cream.