Add the parsnips and carrots to a medium saucepan and just cover with water. Bring to the boil, then reduce the heat, cover and simmer for 7 minutes. Add the sweetcorn, cover and cook for a further 5 minutes.
Drain and add to a blender, along with the milk and butter. Blend until at your desired consistency, adding a little more milk if necessary.
Tip: You can use breast milk or formula in place of whole milk.