Soup: Place the butter in a saucepan over a moderate heat and add the onions. Saute for a 3-5 minutes until they are soft and without colour.
Stir in the remaining vegetables and cook them for a couple of minutes. Add the stock, bay leaf, parsley and rosemary to the pan and increase the heat to high. Bring the stock to the boil, then reduce it to a slow simmer. and gradually stir it in to the saucepan with the vegetables. Leave to simmer for 45 minutes, skimming when necessary
Remove the bay leaf, parsley and rosemary.
Remove the soup from the heat and liquidise it in batches with the cream in a food processor or blender (be careful not to overfill it or it will spill out).
Return the soup to a clean pan and reheat. Adjust the seasoning and consistency by adding a little stock and cream if necessary. You should have a smooth creamy consistency, that pourable and will coat the back of a spoon if not add more stock, water or cream.
To Serve: Distribute the soup among soup bowls. Drizzle a little cream arond each serving or place a teaspoon of creme fraiche in the centre. Sprinkle the parsely over the top and accompany the soup with buttered bread, baguette or cheesey muffins (see recipe).