Place the peeled and cut potatoes into a medium saucepan. Add cold water to the pan until the potatoes are covered by at least an inch. Add a half teaspoon of salt to the water.
Place the saucepan over high heat and bring to a boil. Reduce the heat to medium-low and cover the pan. Continue cooking for about 20 to 25 minutes, or until the potatoes are tender.
When the potatoes are ready, drain the water and place the steaming hot potatoes into a large bowl.
Mash the potatoes with a potato masher or ricer.
Pour the heated plant milk and melted butter over the potatoes, and use a wooden spoon or spatula to beat further. Don't over-work the potatoes or the mashed potatoes will turn gluey.
Add salt, pepper and nutmeg to taste and stir the mixture one last time.
Transfer the potatoes to a serving bowl and serve immediately.