Make up to 2 hours ahead, then gently
reheat, stirring often with a drop more milk
and a dab of butter.
Cut the parsnips into large, fairly evensized chunks: the skinny end will make one chunk, then either halve or quarter the bulky part lengthways, remove the core, and cut into similar-sized pieces.
Bring a large saucepan of salted water to the boil, tip in the parsnips and cook briskly for 10-15 minutes, half-covered, until tender but not slushy. Drain well, then return parsnips to the saucepan.
Push the parsnips to one side and put the butter, spices and plenty of ground black pepper into the space. Return the saucepan to a very low heat and let the butter melt, the spices warm through and the parsnips continue to dry for a few minutes.
Now add the milk and oil and mash the parsnips vigorously, until smooth. (They won’t look as smooth as potato mash but a quick taste will tell you if there are any lumps left.) Adjust the seasoning, if necessary, and serve immediately.