Melt the butter in a large pan, add the onion and potato and cook over a very low heat for 5 minutes.Add the
stock, and bring to the boil, then reduce the heat and simmer for 20 minutes, or until the potato is cooked.
Add the courgettes, bring back to the boil and simmer for 5 minutes. As soon as the courgettes are cooked
remove the pan from from the heat and stir in the almonds, cream and milk.
Puree in a blender, then reheat gently and season to taste.