Preheat oven to 180°C/350°F, and set the rack in the middle position.
Separate the four eggs.
In a large bowl, combine together the almond flour, psyllium husk, baking powder, salt, zaatar, sumac and nigella seeds (if used).
In another bowl mix the egg yolks and melted butter with the dry ingredients and mix everything together.
In another bowl, beat the egg whites (make sure no egg yolks are involved) using a stand or hand mixer until stiff peaks form (watch the video tutorial), it takes about 2 to 3 minutes.
Gently fold the almond-egg yolk mix in the whisked egg whites, in batches, and mix gently until you obtain a dough of one texture. Note that the dough will look first loose but a few seconds it will come together in a uniform ball.
Line an oven sheet with parchment paper, and transfer the dough to it. Sprinkle some sesam seeds on top of the loaf. Bake in the preheated oven to 180°C/350°F for 30. Check your oven before the mentioned time.
Remove from the oven, leave it to cool down completely before slicing to avoid a gummy texture.
You can turn the bread into crackers: After the bread has totally cooled down, turn it into crackers by slicing it very thin. Transfer to an oven sheet lined with parchment paper, distribute the slices in an even layer, bake in a preheated oven to 160 C/ 320F for 12 to 15 minutes until all the moisture is removed, and to be honest, I like the crackers even more than the bread. A prefect accompaniment to dips, scrambled eggs, labneh or just smother it with butter.