In a large bowl, combine olive oil, ground cumin, paprika, turmeric, cinnamon, black pepper, salt, coriander, minced garlic, and lemon juice. Whisk until well blended, creating a vibrant and aromatic marinade.

Add chicken thighs to the bowl, ensuring each piece is generously coated with the marinade. Cover the bowl with plastic wrap and refrigerate for at least 1 hour, though marinating for up to 8 hours will yield even more flavor.

Preheat your grill pan or oven to medium-high heat, aiming for about 425°F if using the oven.

Place marinated chicken thighs on the hot grill or in the oven. Grill for 5-6 minutes on each side, or roast in the oven for about 25-30 minutes.

Once cooked, remove the chicken from the heat and let it rest for about 5 minutes. Then, slice the chicken into thin strips.

Prepare the creamy garlic sauce by combining plain Greek yogurt, mayonnaise, minced garlic, lemon juice, and salt in a mixing bowl. Whisk until smooth and creamy.

To serve, take warm pita or flatbread and layer in the sliced Chicken Shawarma. Drizzle the garlic sauce over the top.