Heat the olive oil in a large
saucepan and slowly fry the
carrots, onion and celery until soft
and dark. This will take about 20
minutes but it’s worth it – the slow
cooking gives a lovely taste. Add
the garlic, chard stalks and half the
parsley, and stir to prevent sticking.
Stir in the tomatoes and cook for
10 minutes or until reduced.
Add half the Swiss chard leaves,
half the cavolo nero, three-quarters
of the beans, and the boiling stock.
Bring to the boil, then reduce the
heat. Simmer for 30 minutes. Pour
in more stock if needed – don’t add
too much – it should be thick.
Add the remaining Swiss chard
and cavolo nero and blanch briefly
so they remain green and crisp.
Season when slightly cooled.
Purée the remaining cannellini
beans coarsely in a blender with
some of the cooking liquid. Add
to the soup – it should be very
green. Stir in the herbs and serve
hot with Parmesan and a drizzle
of extra virgin olive oil.