In a large mixing bowl, combine cumin, coriander, paprika, turmeric, cinnamon, salt, black pepper, and minced garlic. Add the chicken thighs and coat them thoroughly with the spice mixture. Let it marinate for at least 30 minutes, or up to 4 hours in the refrigerator.

In a large, deep skillet or Dutch oven, heat the olive oil over medium-high heat. Add the marinated chicken thighs and sear for about 4 minutes on each side, until lightly browned. Remove the chicken and set aside.

In the same skillet, add the diced onion. Sauté for 3-4 minutes until softened and translucent.

Add the basmati rice to the skillet with the onions, stirring to coat the rice in the residual oil and spices, for about 2 minutes.

Pour in the chicken broth, bringing the mixture to a boil. Reduce the heat to low, cover with a lid, and let it simmer for about 10 minutes.

After 10 minutes, return the chicken thighs to the skillet, placing them on top of the rice. Cover again and cook for an additional 10-15 minutes, or until the rice is tender and the chicken is cooked through.

Remove from heat, letting it sit for 5 minutes. Fluff the rice with a fork.

In a small bowl, mix the plain yogurt and lemon juice together. Serve the shawarma chicken and rice with a drizzle of the lemon yogurt sauce on top. Garnish with fresh parsley.