In a pot, cook the sweet potatoes in water. Make sure they are just submerged. Add some salt to the water and cook the sweet potatoes for 15-20 minutes until they become tender.
Once the sweet potatoes are done, drain them and let them dry in the pot for a short time.
In a saucepan, heat the milk and butter.
Mash the sweet potatoes and add the warm milk and butter to create a smooth puree. Season with salt and pepper. Add the coarsely chopped turnip greens and half of the Parmesan cheese.
Sprinkle the remaining Parmesan cheese on top.
Serve immediately, possibly with roast chops or crispy chicken thighs.