Peel and finely chop the onion. Trim, peel and finely chop the parsnips. Warm 1 tbsp oil in a pan over a very low heat. Add the chopped veg. Season well with salt and pepper. Cover and gently cook for 15 mins till the veg are soft but haven’t picked up any colour. Stir occasionally.
Dissolve the stock cube in 750ml boiling water. Peel and crush the garlic. Cut a small slice from your apple. Finely dice and set aside for garnish. Coarsely grate the rest of the apple, including the skin. Discard the core and pips.
Stir the garlic and grated apple into the veg. Add 1 tsp garam masala. Cook and stir for 1 min till the pan smells sweet and aromatic. Stir in the hot stock. Pop the lid back on, bring the soup to the boil and simmer for 10 mins till the veg are very soft.
Ladle the soup into a blender and blitz till smooth (or use a hand-held blender).Taste and add more salt and pepper if you think it needs it. Ladle into warm bowls and garnish with the diced apple.