- 1 1/2 pounds Russet Potatoes (peeled and cut into 2-inch chunks)
- 1 1/4 teaspoons Kosher Salt (or to taste)
- 1/4 cup Salted Butter (cut into pieces, softened)
- 4 ounces Cream Cheese (softened)
- 3/4 cup Parmigiano-Reggiano (finely shredded)
- 1/2 cup Sour Cream
- 1/4-1/2 cup Milk (warmed)
- 3/4 teaspoon Fresh Thyme (chopped)
- 1/4 teaspoon Freshly Ground Black Pepper
- Pinch Nutmeg
- Paprika (optional)
- 1/2 teaspoon Fresh Chives (chopped)
- Preheat the oven to 350°F. Add the Potatoes to a large saucepan and cover with cold water by at least 1 inch. Add 1 teaspoon of the Salt and bring to a boil. Reduce the heat to medium and cook, partially covered until the Potatoes are very tender, 12 to 15 minutes. Drain and return the Potatoes to the pan.
- Break up the Potatoes with a masher or a handheld mixer on low speed. Gradually add 3 tablespoons of the Butter and beat until incorporated. Gradually add the Cream Cheese, Parmigiano-Reggiano, and Sour Cream, beating well after each addition. Gradually add the Warm Milk, 2 tablespoons at a time, until incorporated and the Potatoes are fluffy and light. (You may not need all the Milk). Stir in the Thyme and remaining 1/4 teaspoon Salt, or more to taste, and the Pepper and the Nutmeg.
- Butter an 8×8-inch baking dish. Spoon the Potatoes into the dish, smoothing the top. Use a small spatula or fork to create peaks on the surface to aid browning.
- Sprinkle the top with the Paprika, if desired. Cut the remaining tablespoon of Butter into small pieces and sprinkle them over the Potatoes. Bake for 30 minutes, or until lightly browned. Sprinkle with Chives and serve warm (if baking the Potatoes directly from the refrigerator, increase bake time 1 hour).