In a pan of salted boling water, cook the parsnips and potatoes for approx 10 mins, until just tender. Drain well, then pass through a potato ricer (or mash well) and leave to cool.
Put the mashed veg and 2 cups flour in a large bowl. Grate in a little fresh nutmeg, season well with salt and pepper and mix together lightly. Break the egg in the bowl. Bring together with your hands and knead to a dough, adding a little more flour if needed. The dough should be light, almost pillowy to touch and not too moist. Don't over knead it.
Divide the dough into 4. On a lightly floured work surface use the flat of your hands to roll and shape the pieces into sausage shapes about 2cm in diameter. Cut into 2cm lengths. Roll roughly into balls. Take a ball and hold it over your finger. Use the prongs of a fork to press down into the gnocchi to form the traditional pattern.
In a pan of salted boling water, cook for 3-4 mins, until the gnocchi rise to the top. Drain. Place on a baking tray, patterned side up and grill until lightly browned on top.
To make the dressing, gently warm all the ingredients excet the parmesan in a small pan until the leaves are just wilted. Pour over the gnocchi and scatter with parmesan to serve.