Boil the chicken with the black pepper, salt, garlic powder, onion powder, and cinnamon until completely cooked.
Discard the liquid and shred the chicken.
To a pan on medium to high heat, add the sliced onions and let them wilt without any oil, and they start to turn into a light pink color.
Add the oil and cook on medium heat for 5 minutes.
Add the shredded chicken and the remaining seasonings (sumac,7 spice, salt, cinnamon) and mix.
Adjust sumac (for tanginess) and salt to your liking, and sauté for another 3-4 minutes.
Add toasted nuts if you like and remove from heat.
Add your mini buns to a lined baking pan or tray and slice in half.
Add the entire filling and top with your desired amount of mozzarella.
Top with the other side of the buns and brush melted butter on top.
Sprinkle with sumac and bake at 450, covered, for about 5-10 minutes or until cheese is melted.
Check at 5 min mark.