In a mixing bowl, combine olive oil, minced garlic, ground cumin, ground coriander, smoked paprika, ground turmeric, ground cinnamon, cayenne pepper (if using), and salt and pepper. Squeeze in the lemon juice, mixing until a smooth marinade forms.

Slice your onions and layer them evenly at the bottom of the slow cooker.

Next, take your chicken thighs and coat them thoroughly in the prepared marinade, then place the marinated chicken directly on the onions in the slow cooker.

Cover the slow cooker and cook on low for 6 hours or on high for 3 hours.

Once the cooking time is up, remove the lid and use two forks to shred the chicken right in the slow cooker.

Finally, serve your succulent Slow Cooker Chicken Shawarma in warm pita bread or over rice.