How to Make It
Combine the potatoes, milk, cream, garlic and thyme in a large saucepan and bring to a boil. Reduce the heat slightly and simmer until the potatoes are tender, about 20 to 25 minutes. Drain the potatoes, reserving the cooking liquid.
Transfer the potatoes to a medium bowl and mash with a fork, adding the nutmeg, olive oil, butter and Parmesan. Add about half of the reserved cooking liquid, mixing well, then add additional cooking liquid if necessary until the potatoes are the consistency you like. Season with salt and pepper to taste.