Season the cod and chill until needed. Heat the olive oil in a medium frying pan, then fry the chorizo over a medium heat for 1 minute until you see a good amount of fat. Tear the bread into pieces and add it to the pan. Toss the bread with the chorizo and cook for 2 minutes until the bread is red with the chorizo oil. Tip on to a plate and leave to cool.
Preheat the oven to 200°C/fan 180°C/gas mark 6. Transfer the bread and chorizo to a food processor and blitz into crumbs. Add the parsley, lemon zest and lots of freshly ground black pepper, blitzing briefly to thoroughly combine the ingredients.
Line a baking tray with greaseproof paper and add the fish. Spoon the chorizo mixture on top of the fish fillets and press down firmly. Bake for 10-12 minutes, until the fish is cooked and the crust is crisp.
Meanwhile, heat the oil in a medium pan. Add the shallot and garlic and cook over a medium heat for 3 minutes, stirring frequently. Stir in the tomato purée, sugar, treacle and red wine vinegar. Add the beans and fill the empty can halfway with water. Add to the pan, then bring to the boil, cover and cook on a low heat for 15-20 minutes, until the sauce has thickened.
Heat the oil in a medium frying pan. Add the garlic and chilli flakes and cook for 1 minute until fragrant, but not coloured. Add the spinach in two batches, waiting for the first batch to wilt before adding the second. Cook for a couple of minutes and remove from the heat. Add the lemon juice and season well. Add the beans to 2 plates, top with the spinach and fish and serve.