Finely chop the onions and garlic
Heat the olive oil and butter in a saucepan and gently saute the onions for about 10 minutes until soft. Make sure not to get any colour on them.
Add the garlic, ginger, cardamom pods, cumin and cayenne and stir for a couple of minutes.
Add the parsnips and stir until well coated in the spices. Pour in the stock, season with salt and pepper and simmer until the parsnips are very soft – about 15 minutes.
Blend using a stick blender until smooth.
Add the milk and some further seasoning and heat through. If the soup is too thick add some more water.