Boil a kettle. Dissolve the stock cube in a jug with 100ml boiling water. Heat a large saucepan filled with salted boiling water on a high heat. Add the rice and boil for 25- 30 mins, until cooked, then drain.
Meanwhile; finely slice the leek into half-moons. Quarter the mushrooms. Finely chop or crush the garlic.
Heat a large frying pan with 2 tbsp oil on a medium heat. Add the leek, mushrooms and garlic, then cook for 5 mins, until softened and slightly caramelised. Drain the beans, rinse, then add to the pan with the stock and cream. Season with sea salt and black pepper; simmer for 10-15 mins.
Finely chop the parsley. Thinly slice the sundried tomatoes. Add the spinach, sundried tomatoes, pesto and half the parsley to the beans for the last 5 mins of cooking time.
Reboil the kettle. Cut the broccoli into florets. Heat a large saucepan filled with salted boiling water on a high heat. Add the broccoli florets and boil for 3-4 mins, until cooked, then drain.
Serve the bean casserole with the rice and broccoli. Garnish with the remaining parsley.