Peel and chop 2 pounds of potatoes, place in cold salted water, bring to boil. Cook for 15-20 minutes until fork-tender. Drain and let sit.

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

In a bowl, combine 4 tablespoons butter and ½ cup heavy cream. Microwave until melted and warm, then stir.

Mash drained potatoes until smooth. Fold in melted butter mixture, ½ cup Parmesan cheese, 1 teaspoon salt, ¼ teaspoon black pepper, and 2 egg yolks until combined.

Spoon mixture into a piping bag fitted with a star tip. Pipe mounds on the baking sheet, spaced apart.

Brush tops with melted butter. Bake for 15-20 minutes until golden brown and crispy.

Garnish with chives or parsley and sprinkle with sea salt. Serve hot.