Melt the butter in a large saucepan over medium heat. Add the onion and fry until soft, about 5 minutes. Add the parsnips, garlic and curry powder.Stir to blend and cook for a couple of minutes to release the flavours.
Dissolve stock cube in boiling water in a jug Stir into pan.
Simmer for 15 minutes or until parsnips are well cooked and soft.
Remove from the heat and blend with an electric hand blender until smooth.
Stir in the cream and warm through.( Alternatively use a food processor to blend soup, return to a clean pan, stir in cream and reheat.)
Season to taste and garnish with the chilli flakes or paprika.