Put two tablespoons of oil in a large frying pan over a medium heat and, once hot, add the onion and cook, stirring occasionally, for eight minutes, until really soft and starting to turn golden. Add the second garlic clove and the chilli, cook, stirring, for a couple of minutes, then tip in the butter beans and all their remaining liquid. Simmer for about 10 minutes, until the beans are soft and the stock has reduced a little, then stir in the salsa verde and salt to taste. Take off the heat and serve at once with toasted ciabatta to mop up the juices.