- 3 pounds Idaho potatoes, peeled and cut into 1-inch pieces
- 1 3/4 teaspoons salt
- 6 tablespoons unsalted butter, cut into pieces
- 3/4 cup milk
- 1/4 teaspoon plus a pinch freshly ground white pepper
- 3/4 pound Cantal cheese, outer hard rind removed, coarsely grated or crumbled
Place the potatoes and 1 teaspoon of salt in a heavy medium pot, cover with water by 1 inch, and bring to a boil. Reduce the heat to a simmer and cook until the potatoes are fork-tender, 20 to 25 minutes. Drain in a colander.
Return the potatoes to the pot, set over low heat, and add the butter. Using a potato masher, mash the butter into the potatoes. Add the milk, the remaining 3/4 teaspoon salt, and the pepper and mash with the potato masher over medium-low heat to incorporate the ingredients and achieve a light texture, 4 to 5 minutes. Add two-thirds of the Cantal and stir until melted and smooth.
Serve immediately, with the remaining cheese crumbled on top.