To make the marinade:

• Cut each chicken breast in half horizontally, then cut it into 1-inch / 3-cm-thick strips.
• Combine the salt, paprika, cumin powder, cardamom powder, ginger powder, cinnamon powder, grated nutmeg, white pepper, onion powder, garlic powder, coriander powder, cornstarch, and crushed garlic.
  
• Add the yogurt, tomato paste, oil, lemon juice, orange juice, and vinegar. The lemon, orange, and vinegar provide acidity that will help tenderize the chicken. Whisk together until well combined and homogeneous.
  
• Add the chicken strips and make sure the pieces are evenly coated in the marinade. Cover with plastic wrap and refrigerate for 24 hours, or for a minimum of 4 hours.
  
• To make the garlic sauce:
• In a saucepan, combine the cornstarch and water. Place over high heat and whisk continuously until the mixture comes to a boil and thickens completely. Remove from the heat and set aside to cool completely.
• Combine the garlic cloves, ½ cup water, lemon juice, and salt. Purée until smooth; the garlic flavor will become more pronounced after blending. Stop to scrape down the sides of the bowl as needed.
• Add the cornstarch paste to the food processor and pulse a few times to combine it with the garlic mixture.
• Slowly add the oil in a steady, thin stream while the food processor is running. Continue adding the oil gradually until you have used it all. It is crucial to add the oil slowly while the food processor is running to help emulsify the garlic sauce.

  The end result should be loose and fluffy, but not runny. If the sauce is too thick, add 3 tablespoons of oil and pulse a few times to incorporate it. Taste and adjust the salt according to your preference.
  
• Preheat the oven to 220°C/430°F.
• Add the chicken shawarma and the marinade to a large baking dish. The chicken will absorb some of the marinade, but there will be some left over, so add everything to the dish and spread it out evenly.

  Bake until the chicken is browned and crisp around the edges, about 50 minutes. For a crispier, more charred top, turn on the broiler at the very end and broil for 2–3 minutes, until the chicken is lightly charred and nicely browned.

• Optional: Add a Smoky Charcoal Effect

  This step is optional, but highly recommended! It gives the shawarma an irresistible smoky flavor, making it taste as though it has just come off a charcoal grill—without the hassle of firing up the barbecue at home.

  Start with a small piece of natural lump charcoal. Avoid charcoal that contains added chemicals. Light the charcoal directly on your stove and let it heat until you see white ash appearing on the lit end.

  Carefully transfer the hot charcoal to a small, heatproof cup and place it in the center of the cooked shawarma. Add 3 tablespoons of ghee to the charcoal. It will immediately produce dense, dark smoke.

  Immediately cover the shawarma with a lid and leave it covered for 1 minute, allowing the smoky aroma to infuse the meat. This simple technique gives your shawarma an intense, authentic charcoal-grilled flavor.
• To assemble the chicken shawarma wraps: Use Arabic bread, saj bread, or another thin flatbread. Spread a generous layer of garlic toum over the bread, then layer on the chicken, pickles, fries, and some shredded romaine lettuce. Wrap it tightly, then place it in a panini press or in the oven until crisp and golden.