Place potatoes in a large saucepan and cover with water. Bring to a boil. Reduce heat; cover and simmer 15-20 minutes or until tender. Drain. Over very low heat, stir potatoes 1-2 minutes or until steam has evaporated. Remove from heat.
Preheat oven to 400°. Press potatoes through a potato ricer or strainer into a large bowl. Stir in the egg yolks, milk, butter, salt, pepper and nutmeg.
Using a pastry bag or heavy-duty resealable plastic bag and a large star tip, pipe potatoes into 6 mounds on a parchment-lined baking sheet. Brush with beaten egg. Bake 20-25 minutes or until golden brown.
