This is a dish that is very old and traditional in Palestinian cuisine.
Seasoning food with Zaatar is very common in Palestinian cuisine especially in the kitchens of Bethlehem and its nearing villages such as Beit Jala and Beit Sahoor. It is believed to have originated there and moved from there to Jerusalem, where seasoning with zaatar became also very widespread.
The shifting of people from their villages and cities in 1948 and 1967 to eventually settle in Lebanon, Syria and Jordan had carried with them these foods making them popular in their eventual destinations. Ever since then, varieties of Zaatar chicken had become common throughout the Levant, but this remains the traditional recipe as it was first prepared in Bethlehem.
While the original recipe fries the potatoes in one version, and bakes the potatoes raw with the chicken in the second version, I personally season the potatoes with zaatar to pack more of that flavour into them, then roast them separately. I then add them to the finished roasted chicken as I find this to be a more flavoursome option. This way the texture of the potatoes remains crunchy instead of the mushy baked ones, and less drenched with oil as is the case of the fried potatoes. Try it this way and see how you guys are going to really love it.
Zaatar Chicken is a very simple dish packed with flavour. It is one of those concoctions that you can prepare with ease yet please every single one of your family members.