Place chicken in a large soup pot and cover with water. Add onion, carrots, celery, garlic, salt and pepper. Cook over medium heat for about 45 minutes or until chicken is very tender. Remove chicken to a platter. When chicken is cool enough to handle, chop into bite sized pieces; set aside.
Bring chicken broth to a boil. Meanwhile, cut slightly thawed, frozen biscuits into eighths. Place flour in a zip top bag and shake biscuit pieces in flour until well coated. Drop pieces into boiling broth. Reduce heat to medium and cook for 10 to 12 minutes – do not stir.
Add chicken and half and half and cook for an additional 10 minutes on low heat until thickened, stirring occasionally. Season to taste and serve.