Warm 4 tbsp of olive oil in a large heavy pan over a medium heat. Dice the onion, carrot and celery and add to the pan with a pinch of salt.
Sweat the mix down for a few mins, then add the tomato purée, bay leaves, rosemary, chilli and 2 of the garlic cloves.
Cook for another few mins until fragrant. Break up the plum tomatoes into a bowl, then add to the pan along with the vegetable stock.
Drain one of the tins of beans and use a fork to mash them up into a paste. Add to the pan and mix well until it becomes slightly thick. Cook for about 30 mins.
Whilst the ribollita cooks, strip the cavolo nero leaves firmly from the stalks and roughly chop them. Add the cavolo nero and your second tin of beans to the pan and cook for a further 20 mins.
Meanwhile, cut 4 thick slices of ciabatta and toast. Rub the toast with the remaining clove of garlic.
Once the ribollita is ready, add salt and pepper to taste.
Now the important bit - place a slice of the garlicky toast in the bottom of each bowl and pour the stew on top. Leave it for a few mins until the bread goes soft (trust me). Add a drizzle of olive oil and a sprinkle of cheese (if you like). Enjoy.