If you're using dried beans, soak the flageolets overnight in cold water, then drain, cover with fresh water and cook until tender but still holding their shape. This will take anything from 1-2 hours.
Heat the oil in a deep, heavy-based casserole dish and fry the sausage pieces until golden brown.
Add the garlic and rosemary, then turn down the heat and stir in the onions.
Cover with a lid and cook gently for 15 minutes until the onions are soft and gently browning, giving the occasional stir.
Pour in the chicken stock, add the cooked, drained beans, and season.
Bring to a relaxed simmer and cook for around 20 minutes, skimming as necessary.
Stir in the cream and kale and mix well, then simmer for 10 minutes with a lid on and another 10 minutes without.
Adjust the seasoning and finish with the chopped parsley.