Prepare potatoes: Peel and cut the potatoes into 1 inch/ 2 ½ cm chunks. Place them in a large saucepan, and cover them with cold water.
Cook potatoes: Bring them to a boil on high heat. Add about ½ tablespoon salt. Boil on medium-high heat for about 15 minutes or until fork tender.
Drain potatoes very well in a colander and return them to the hot pot.
Mash potatoes with the potato masher or ricer.
Heat the milk in a small saucepan or microwave.
Combine: Pour the milk over the potatoes. Add the soft butter, cream cheese, Parmesan, one teaspoon of fine sea salt, and ¼ teaspoon of black pepper. Fold them in gently using a wooden spoon until they are fully incorporated. Feel free to add a bit more warm milk if you want a softer consistency.
Add the truffle oil and stir again without overmixing.
Adjust the taste with more salt if required.
Serve immediately. You could add a tiny extra drizzle of truffle oil if you like, but don't overdo it.