In a large stockpot, add the reserved chicken bones, carcass and cartilage from the roast chicken (or straight out of the freezer if you’ve been saving up the bones).
Pour over the stock, add the onion, celery, carrots, tomato paste, fresh tomatoes, butternut, sweet potato and bay leaves, and bring to a bubbling simmer.
Once bubbling, turn down the heat and simmer for 30–45 minutes, or until the hardest root vegetables are cooked through.
Using a colander, strain the liquid into a heat-proof bowl, keeping the vegetables aside.
Discard the bones, cartilage and bay leaves.
Return the vegetables and the strained liquid to the pot.
Bring the soup to the boil and add the pasta.
Once the pasta is almost cooked, add the baby marrows, peas and cannellini beans and cook for a few minutes until the baby marrow is soft but not too mushy.
Remove the pot from the heat and add the baby spinach, stirring it in so that it wilts.
Serve in giant soup bowls with chunks of rye sourdough, or seed crackers for a low-carb option, and a liberal grating of vegan or good quality organic or grass-fed dairy parmesan.