Place the parsnips, and potato in a pan with cold water. Bring to the boil and and then drop the temperature down to medium. Cook for 10-15 minutes until tender.
Once cooked, drain well - be sure to remove anyy traces of water.
Combine the cooked parsnips in a bowl along with the olive oil, milk, Parmesan and salt and pepper and mash well. Alternatively, place the ingredients in a food processor and mix until smooth and creamy.
If you find that it’s a little “stiff” - thin it out with some extra milk.