Pat chicken dry with paper towels. Place chicken, breast-side down, on a chopping board. Use kitchen scissors to cut along each side of the backbone, then remove and discard backbone. Turn chicken over and cut in half through the breast bone. Place chicken halves in a large stockpot and cover with cold water 5cm above chicken. Cover with a lid. Place over medium-high heat and bring to the boil.
Add parsley stalks, and half each of the garlic and vegetables, except spinach, to stockpot. Cover and return to the boil, then reduce heat to medium-low and simmer, uncovered and skimming any scum from surface, for 1 hour or until chicken is cooked through. Stand for 20 minutes.
Remove chicken from stockpot and place on a chopping board. Discard skin and bone, then shred the meat. Strain chicken stock, discarding solids, into a large saucepan. Bring to the boil over medium-high heat and reduce, if necessary, to 1.5 litres.
Add chicken and remaining garlic and vegetables, except spinach, to pan. Return to the boil, then reduce heat to medium and simmer for 10 minutes or until vegetables are tender. Season well.
Finely chop parsley leaves. Divide spinach among bowls, then ladle over soup. Scatter over parsley and serve with bread.
Tip 1: Add 1/2 cup cooked pearl barley or cooked small pasta shapes to this recipe with the shredded chicken. Tip 2: Add a 400g can of creamed corn with the shredded chicken for a creamier soup. Tip 3: Freeze the soup for up to 3 months in airtight containers. Defrost in the fridge overnight before reheating.