With those sweet leeks, fragrant rosemary and succulent chicken, this dish is going to work it all out by itself once you pop it in the oven. You need only put in a bit of effort up top to make it happen, so don't rush the browning. Take your time to get the skin crisp and golden to release all those savoury flavours that will nudge this dish into the comfort zone.
Preheat oven to 180°C fan-forced. Dust chicken in flour and season with salt and pepper. Heat 20ml (1 tablespoon) oil in an ovenproof frypan over medium-high heat. Add chicken, skin-side down, and cook for 5 minutes each side or until golden. Remove from pan and wipe pan clean. While chicken is cooking, continue with step 2.
Cut green tops from leek and discard. Halve lengthways, wash thoroughly and thinly slice. Pick rosemary leaves from their stems and roughly chop. Peel and thinly slice garlic. Rinse and drain butter beans. Boil kettle in preparation for step 4.
Add remaining oil to frypan and return to medium heat. Add leek, rosemary, garlic, salt and pepper and cook, stirring occasionally, for 4–5 minutes or until softened. While leek is cooking, continue with step 4.
Dissolve stock cube in 500ml (2 cups) boiling water. Return chicken to pan with butter beans and stock and bring to a simmer. Cover with a lid and transfer to the oven. Roast for 1 hour or until chicken is tender.
Trim beans and halve. Remove lid from pan and add beans. Return to the oven for 5 minutes or until beans are tender.
Carefully remove pan from oven. Remove chicken from pan and set aside. Add baby spinach and crème fraîche to pan and stir until spinach is wilted. Season to taste. Divide chicken between bowls and serve with beans.