In the bowl of a stand mixer, put semolina, flour, 1 whole egg, 1 egg white, granulated sugar, vegetable oil, yeast and milk.
You can mix everything together with your hands or a wooden spoon or just use the stand mixer with a hook attachment. Mix until the dough gets together for about 5 minutes.
Add water gradually while mixing. You may need to replace the hook attachment with the flat beater since the dough is less heavy after adding water.
Keep mixing on low for about 10 minutes.
Add salt and mix it well.
Add 1 tablespoon of Nigella seeds then mix well. The dough mixture obtained is sticky and very soft.
Cover the dough with plastic wrap and kitchen towel in the same bowl until doubled in volume. This may take 1 to 2 hours (depending on the temperature of your kitchen).
Put the dough in a baking pan lined with parchment paper. Spread it evenly in that pan with a silicon spatula (the thickness is your choice but the thinner, the better as it will rise).
Cover the pan with a clean kitchen towel and let rise again until almost doubled in volume.
Gently brush the surface of the bread (dough) with egg wash.
Sprinkle Nigella seeds on top.
Bake in a 375 °F preheated oven for about 15 to 20 minutes or until golden. You may place the Bread or Khobz Eddar under the broiler in the last 5 minutes of baking to get that golden color.
Let cool a little bit then cut and serve.