Place chicken, onion, celery, salt, basil and pepper in a 10 litre stock pot. Fill stock pot with water until ingredients are fully covered and bring to the boil. Let simmer for 1 and 1/2 hours or until chicken is tender.
Remove chicken from pot with slotted spoon and set aside for later.
Add carrots, courgettes, mushrooms, red pepper, tortellini, chicken stock granules and pasta to stock pot and increase temperature to medium heat.
While pasta and vegetables are cooking, tear chicken apart from bones. Cut up into pieces and add to soup in stock pot. Be sure to add additional water if ingredients are not fully covered. Bring to the boil, then reduce to a simmer for about 10 minutes or just until pasta is cooked. Enjoy.