Pull away any tough stalks from the spinach leaves and leave the spinach to drain in a colander.
Heat the oil in a large saucepan and gently fry the onions and garlic until they are soft but not coloured. Add the spices anfd continue to fry over a low heat for a further 2 minutes.
Now increase the heat and quickly add half the spinach. Allow to wilt, stirring continuosly to prevent from catching before adding the remaining leaves.
As soon as the spinach is soft and tender ( about 5 minutes) remove from the heat and add 285 ml water and the buttermilk. Immediately liquidise and strain into a clean pan.
Gently reheat before serving, add the cream and adjust the seasoning to taste. Do not allow to boil as it may separate and will lose its delicate colour.