To a 3-quart saucepan, add the beans, carrot, celery, onion and clove. Tie the parsley and thyme together and add, along with enough tepid water to cover by about 2 inches. Bring to a boil, then lower the heat and simmer, with lid slightly ajar, for 15 to 20 minutes or until the beans are very soft and have begun to lose their shape. Meanwhile, mix the lemon juice and saffron in a small cup and set aside for 10 minutes.
When the beans are done, lift out the vegetables and herbs and discard them. Drain the beans well, discarding the liquid. Transfer the beans to a medium-size bowl and beat in 1 tablespoon of the butter with a wooden spoon. Then stir in the saffron and lemon juice, and the salt and pepper.
In a small skillet, heat the remaining butter and sauté the shallots over medium heat, stirring constantly for 2 to 3 minutes or until they are translucent, but not brown. Add the puree and beat in 2 tablespoons of the cream (1 more tablespoon may be needed if the texture is too dry), then stir in chopped dill. Taste for salt and pepper. Transfer to an oven-to-table serving dish, cover with aluminum foil and keep warm in a preheated low oven until ready to serve. Garnish with a sprig of dill.
