Preheat the oven to 190°C

In a large saucepan add the oil and butter and place on medium heat.

Add the sliced onions and stir. Cook on medium heat to soften but not colour, for around 8 minutes.

Add in the garlic and fry for 1 minute then stir.

Add the diced swede and potato and coat in the butter and oil. Season with a few twists of salt and pepper.

After you have cut out the stalk of the spring greens, roll them into a sausage shape and chop into fine slices. Add to the pan and stir.

In a separate bowl add the cream, milk, nutmeg and sage. Add a little more seasoning and stir. Add this mixture to the pan and coat all of the veg.

Tip all the contents of the pan into an oven proof dish (24cm by 25cm), cover with tin foil and bake for 1 1/4 -1 1/2 hours. After half of the cooking time, take off the foil and sprinkle over the parmesan and bake uncovered for the rest of the cooking time.

If the top is becoming too brown, place the foil over again. Cooking time will vary if you use a different sized dish. Cook until the swede is soft.