Begin by peeling and chopping the potatoes into equal pieces. Place them in a large pot of salted water and bring to a boil over medium-high heat. Cook for 15-20 minutes until fork-tender, then drain and return to the pot to steam off any excess moisture.

While the potatoes are cooking, preheat your oven to 425°F (220°C) and prepare a baking sheet lined with parchment paper.

In a small saucepan, melt unsalted butter over low heat and warm the heavy cream in another pot.

Drain the boiled potatoes and return them to the pot over low heat. Mash until smooth, then mix in the melted butter, warm cream, grated Parmesan cheese, salt, and black pepper. Finally, add the egg yolks and mix until creamy.

Transfer the potato mixture into a piping bag fitted with a star tip and pipe small mounds on the prepared baking sheet.

Brush the piped mounds with melted butter and bake for 15-20 minutes, or until golden brown and crispy.

Once baked, garnish with chopped chives or parsley and sprinkle with sea salt before serving.