Preheat the oven to 500 degrees F. Place 6 medium russet potatoes directly on the oven rack and bake until soft, about 35 minutes. Split each potato in half and scoop out the flesh; transfer to a large bowl. Add 1½ cups warmed heavy cream, 1 stick cubed salted butter, 1 1/2 teaspoons kosher salt and a few grinds of pepper to the bowl and mash well. Top with more butter.
Photograph by Con Poulos