The River Cafe's winter minestrone

INGREDIENTS

• 2 tbsp olive oil
• 2 medium carrots , roughly chopped
• 1 large red onion , coarsely chopped
• 1 head of celery , coarsely chopped, keeping the leaves
• 1 head of garlic , cloves peeled
• 1kg Swiss chard , leaves shredded and stalks roughly chopped
• a good handful of parsley , finely chopped
• 400g can peeled plum tomatoes , drained of most of their juices, roughly chopped
• 1kg cavolo nero , stalks removed, leaves shredded (or savoy cabbage)
• 410g can cannellini beans , drained and rinsed
• about 700ml boiling chicken or vegetable stock
• a few sprigs of winter herbs such as thyme or sage, chopped
• freshly grated Parmesan
• extra-virgin olive oil , for drizzling