Place potatoes in a medium to large pot and cover with cold water. Add salt and bring to a simmer. Cook until fork tender, about 20 to 25 minutes.

Melt 2 tablespoons of butter and set aside. Preheat oven to 425°.

Drain the cooked potatoes and return to pot. Set over low heat to release steam for a minute.

Add 2 tablespoons of butter and mash the potatoes until smooth. Incorporate nutmeg, black pepper, heavy cream, and salt. Finally, add egg yolks.

Pipe the potatoes onto a cookie sheet using a piping bag or fill a casserole dish and create peaks with a fork. Brush with melted butter.

Bake in the oven at 425°F until nicely browned, about 20 minutes.