Peel and cut the potatoes into large cubes and put into a medium saucepan. Add cold water until the potatoes are covered by at least an inch. Cook for about 15 to 20 minutes, or until you can easily poke through the potatoes with a knife.
Drain the water from the potatoes. To the steaming hot potatoes add oat milk, plant butter, mayo, nutritional yeast, garlic powder, and season with salt to taste.