Place the sliced onions and garlic in the slow cooker. In a small bowl, mix the spices together. Wash and pat dry the chicken. Generously rub the spices over the chicken until completely covered. Add the spice rubbed chicken to the onions, cover and cook on low for 5-6 hours.
When chicken is done, debone the meat and store in a sealable container in the refrigerator for up to 4 days. I store the bones in the freezer until I have enough to make homemade chicken stock.