Season the chicken with the cumin, garlic powder, pinch of salt, and pepper.
Place chicken in a slow cooker, pour the Harissa over the chicken, and cover. Cook on HIGH for 2 hours or LOW for 4 hours.
Remove chicken from the slow cooker and shred with two forks.
Return the shredded chicken to the slow cooker and mix with the sauce.
If using a pressure cooker, follow the same steps but cook on high pressure for 20 minutes. Quick or natural release then shred with two forks.
If using frozen chicken breasts, cook for 25 minutes.
Serve with Tzatziki or over rice and enjoy!