Step 1

Place the potatoes in a pot and add enough water to cover by 2 inches (5 cm). Place the pot over high heat, add 2 tablespoons salt so the water is nice and salty, and bring to a boil. Reduce the heat to maintain a light simmer.

Step 2

Cook until the potatoes are fork-tender, 20 to 25 minutes. Drain the potatoes in a colander.

Step 3

Immediately pass the potatoes through a potato ricer or food mill and back into the pot. Alternatively, you can use the back of a wooden spoon to press the potatoes through the colander or mash them with a handheld potato masher until they’ve very smooth.

Step 4

Place the pot over low heat and stir in the warm cream and butter.

Step 5

Add half of each type of cheese and stir until melted. Then stir in the remaining cheeses. Continue stirring until the potatoes can be stretched with a spoon like melted mozzarella, 4 to 9 minutes.

Step 6

Season with salt and the white pepper. Serve warm.