Remove neck and giblets from chicken cavity and reserve them for another use. Trim away any excess fat.
Chop together parsley, rosemary, fennel seeds and 3 of the garlic cloves. Place mixture in a small bowl and add salt, a generous grind of pepper and the oil. Place about one-third of the mixture inside chicken cavity along with remaining 5 garlic cloves. Spread the rest of the herb mixture over chicken. Place chicken in a large slow cooker. Sprinkle with shallots.
Cover and cook on LOW for 6 hours, or until chicken is tender and temperature in thickest part of thigh measures 165 degrees F on an instant-read thermometer. Cut chicken into serving pieces and serve with cooking juices.