Heat oil in a large, deep pot over a medium-high heat. Add chicken. Cook for 5 minutes, turning occasionally, until lightly browned all over. Remove and set aside. Reduce heat to medium.
Add onion, carrots, celery, turnip, garlic and thyme to pot. Cook for a further 5-7 minutes, stirring occasionally, until lightly browned.
Return chicken to pot with bay leaf, 2 litres (8 cups) water and stock cube. Bring to the boil. Reduce to a simmer and cover with lid. Simmer for 1 hour. Stir in pasta. Simmer, covered, for a further 15 minutes.
Remove from heat. Lift chicken pieces from pot using a slotted spoon. Shred chicken meat and discard bones. Return chicken to pot with parsley. Stir over low heat until hot.

To cook soup in a slow cooker, complete steps 1 and 2 as above, then transfer chicken and vegetables to a slow cooker. Add bay leaf, water and stock cube as directed in step 3. Cook on Low for 7 hours (or High for 4 hours), adding pasta in the last 30 minutes of cooking time. Follow step 4 as above and keep soup warm in slow cooker on low setting until ready to serve.
Freeze individual soup portions in containers. Thaw overnight in fridge and reheat on stovetop or in microwave until hot. Great for a warming office lunch or a light dinner on chilly nights.