Via: Tara Fisher
Drain the soaked beans. Heat the oil in a large saucepan, then add the onion, garlic, rosemary, chilli flakes and bay leaves and stir well. Cover and cook over a low heat for 10 minutes until the onions are soft and translucent but not browned.
Add the beans and 500ml cold water. Bring to the boil, lower the heat, cover and leave to simmer for 1 hour 30 minutes or until the beans are very tender.
Meanwhile, preheat the oven to 190°C/gas mark 5. Slice open the vanilla pod lengthways and scrape out the seeds with the tip of a knife. Using your fingertips, mix the seeds into the soft brown sugar in a bowl. Spread the vanilla sugar out on a baking tray or board. Lay one rasher of bacon on to the vanilla sugar and press down on it to lightly coat it in the sugar, then flip over and repeat on the other side. Lay on a wire rack and repeat with the rest of the bacon slices. Sprinkle them lightly with any remaining sugar. Sit the rack on a baking sheet and bake the bacon for 16-18 minutes until crisp and brown. Remove and leave to cool, then snip into small pieces.
Add the stock to the pan of cooked beans, bring to the boil and simmer uncovered for 10 minutes, then remove the bay leaves. Leave to cool slightly then blend, in batches if necessary, until smooth. Pass through a fine sieve back into a pan. Stir in the cream if using, and season generously. Bring back to a gentle simmer.
To serve, ladle the soup into warmed bowls and garnish with a swirl of extra-virgin olive oil, ground black pepper and the crumbled candied vanilla bacon.