Heat the olive oil in a casserole dish over a medium heat until hot. Sweat the onion and garlic for 6-7 minutes, stirring frequently, until softened. Add the mushrooms, beans and pumpkin then cover with the stock. Add the bay leaf and bring to the boil over a moderate heat.
Reduce the heat to a simmer and cook gently for 35-40 minutes until the pumpkin and beans are soft. Adjust the seasoning to taste, then discard the bay leaf. Garnish the dish with a few saffron strands before serving.