- 4 1/4 lb russet potatoes, peeled and cut in half
- 1/2 cup mascarpone cheese, softened
- 3/4 cup milk, plus 1/4 cup
- 1 egg yolk
- Salt and freshly ground pepper
- Pinch of cayenne
- 1 cup (2 sticks) butter, plus 4 Tbsp, softened and cut into pieces
Bring a large pot of water to boil over high heat. Add the potatoes, reduce heat to medium-low, and simmer until tender when pierced with a knife, about 20 minutes. Transfer potatoes to a colander and drain thoroughly, about 5 minutes.
Preheat oven to 425°.
In a large bowl, add mascarpone cheese, milk, and egg and stir until well blended. Season with salt, pepper and cayenne and stir to combine.
In another large bowl, add potatoes, butter, and season with salt and black pepper. Mash butter into potatoes with a potato masher until fluffy. Add mascarpone mixture and fold to combine.
Spread mashed potatoes into a 9”x13” baking dish. Smooth the top and use the tip of a spatula to lightly press the potatoes and lift up to create little peaks and valleys in the top. Bake in oven until potatoes are heated through and top is golden brown, about 20 minutes. Serve or let cool, cover with aluminum foil and refrigerate for up to 2 days.
When ready to eat, pour 1/4 cup milk over potatoes, dollop 4 tablespoons butter on potatoes, cover with foil and heat in a 350° oven for 20 minutes.