Here's the thing about shawarma spice mix recipes. If you look up a dozen recipes you will, in fact, get a dozen different recipes. Some only differ in measurements while others introduce spices not commonly included. You can also buy pre-made shawarma mix from about half a dozen spice companies. They don't list their recipes but they probably all taste a little different. So, we're going to have to agree that it's one of those hometown, regional, tribal, family-specific kinds of things and nobody is really sure what's correct. Most places consider shawarma a sandwich and the meat (beef, lamb, chicken) is roasted on a spit with the spice. So chickpea shawarma is not as common but they just don't know what they're missing.