Add the cubed potatoes to a large pot of cold water, and rinse the potatoes 2 or 3 times until the water runs clear.
3 lbs. Yukon gold potatoes, washed, peeled and cut into 1-2 inch cubes (or Russet Potatoes)
Cover the potatoes with fresh cold water and add a generous pinch of kosher salt. Don't be shy here, add a really big pinch(s) of salt!
Kosher salt, to taste
Bring the potatoes to a boil over medium-high heat, then reduce the heat down to maintain a simmer over moderate heat until the potatoes are tender, about 15-20 minutes.
Meanwhile, make the Parmesan cream sauce. In a saucepan over medium heat, melt the butter. Whisk in the flour and whisk for about a minute to get rid of the floury taste.
8 Tbsp. butter, unsalted, 2 Tbsp. all-purpose flour
Then gradually whisk in the heavy cream and milk in a steady stream.
3/4 cup heavy cream, 3/4 cup whole milk
Bring to a simmer, then add in the Parmesan and whisk until smooth and remove from heat. Sauce will be thick and creamy, similar to an Alfredo sauce texture.
1 cup Parmigiano Reggiano, finely grated using a micro plane
Drain and rinse the potatoes under hot water for 1 minute (this is to rinse excess starch)
Pass the warm potatoes through a potato ricer, or food mill, over the pot. If you don't have either, use a potato masher.
Fold in the Parmesan cream sauce, season generously with more salt, white pepper and chives on top.
white pepper, to taste, garnish: fresh chives, thyme, etc.
If looser potatoes are desired, heat some milk in a sauce pan just until warmed and slowly add to the potatoes and fold until desired consistency is reached.
Serve warm and enjoy!