Peel and chop the potatoes into equal-sized pieces, cover with salted water, boil for 15-20 minutes until fork-tender. Drain and let sit to evaporate excess moisture.

Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper.

In a small saucepan, melt 2 tablespoons of unsalted butter and warm the heavy cream over low heat.

Return the drained potatoes to the pot and mash until smooth. Stir in warm cream, melted butter, Parmesan, salt, pepper, and egg yolks.

Transfer the mixture into a piping bag fitted with a star tip and pipe swirls onto the prepared baking sheet.

Brush the piped potatoes with remaining melted butter and bake for 15-20 minutes until golden brown and crispy.

Remove from the oven, garnish with fresh chives or parsley and sprinkle with sea salt. Serve immediately.