Preheat oven to 375°.
Peel and quarter potatoes.
Add potatoes to large pot, cover with water, add a pinch of salt, and bring to a boil.
Once boiling, reduce to a simmer and cook for 10-12 minutes.
Drain potatoes and rinse under cold running water.
Rice potatoes into a large bowl. Add melted butter, milk, salt, pepper, garlic powder, and nutmeg. Mix until well combined.
Whisk egg yolks and egg, then add to the mashed potatoes. Stir until well mixed.
Using a pastry bag fitted with a star tip, pipe the potatoes onto a large baking sheet lined with parchment paper.
To Store: Arrange in a single layer in an airtight container and refrigerate for up to 3-5 days.
To Freeze: Pre-freeze in a single layer on a baking sheet. Transfer to a freezer safe container and freeze for up to 3 months.