Fry the sliced onions in a pan with some olive oil, garlic, broad beans, chicken stock and the bouquet garni for about 10 minutes.
Clean the leeks, slice them and stir-fry with a little bit of olive oil, salt and pepper.
Cover and cook until the leeks are well done.
Allow to cool.
Remove the bouquet garni from the soup and liquidize in a blender.
Add fresh cream, salt and pepper and leave to chill