Melt the better in a heavy saucepan over a low heat to prevent it from burning. Add the onions and garlic, stirring frequently for 15-20 minutes until the onions are soft and translucent.
Add the saffron and cook, uncovered, for 3-4 minutes. Add the ground almonds and cook, stirring continuously, for 2-3 minutes. Add the stock, sherry and 1 tsp salt and plenty of pepper. Bring it to the boil and then simmer gently for about 10 minutes.
Process the soup in a blender until smooth, then return it to the rinsed pan. Reheat slowly without allowing the soup to boil, stirring occasionally. Check the seasoning.
Ladle the soup into heated bowls, garnish with the toasted almonds and a little parsley and serve immediately.