Preheat oven to 350F. Line a 9”x13” baking dish with wax paper. If helps to grease the wax paper with palm shortening, but isn’t completely necessary (I usually don’t bother).
Using a standing mixer, beat the egg whites until stiff peaks form (you can also do this with a hand mixer or even by hand if you prefer).
In a small bowl, combine egg yolks, maple syrup, cinnamon, coconut milk, and arrowroot powder.
Gently pour the yolk mixture onto the egg whites. Add about half of the sifted coconut flour. Gently fold the mixtures together. As they start to combine, add the rest of the sifted coconut flour. Fold until fully combined.
Pour batter into prepared baking dish and spread out evenly. Dust with extra cinnamon, if desired. Bake for 18 minutes, until golden brown and spongy to the touch.
Very shortly after removing from the oven, lift the flat-bread out of the pan (using the sides of the wax paper, or just flip the whole thing over onto a cutting board). Carefully peel the wax paper off the bottom. Slice into squares and enjoy warm or refrigerate for later.