Preheat oven to 400˚F. Line two baking sheets with parchment or a silicone liner.
Peel the potatoes and cut into 1 inch pieces. Place in a saucepan and cover with water. Bring to a boil and simmer until the potatoes are tender, about 20 minutes. Drain and transfer the potatoes to a large bowl.
Mash the potatoes until completely smooth using a potato ricer or masher. Fold in the egg yolks, one at a time, while the potatoes are still warm. Fold in the softened butter and cream. Season to taste with about ¾ teaspoon salt and pinches of freshly ground black pepper and nutmeg.
Transfer the creamy potatoes to a large piping bag fitted with a ½ inch star tip. Pipe a small round, enclosed circle of potato about 2 inches wide on the prepared baking sheet. Around the edge of the circle, pipe 3 layers tall, leaving a cavity in the center. Repeat with the remaining potato mixture to make about 20 Marquis Potatoes.
Bake the potatoes in the preheated oven until the tops are golden, about 20 minutes, rotating the baking sheets around the 10 minute mark.
Once golden, transfer the baked Marquis Potatoes to a serving platter using a spatula. Serve immediately with desired sauce.