Wash, peel, and cube the potatoes and cover with cold salted water.  Bring to a boil, then simmer for 12 to 15 minutes or until fork tender.  Drain and dump into a large bowl.  Let them release steam for a few minutes as it will help get rid of extra moisture.

Add a few cooled off spuds at a time to the potato ricer.  Squeeze the ricer to press the spuds out through the bottom.  Use a knife to scrape them off the ricer and into the bowl.  Repeat this process until all the spuds are done.  (Using a potato ricer will make them lump free and fluffy.  If you don't have a potato ricer, mash them until all the lumps are out.)

Separate the egg whites from the yolks.  Place the yolks on top and the whites in a small bowl to use as a wash later.

While they are still warm, add the butter, heavy cream, salt, white pepper, garlic powder, and nutmeg.  Stir until well combined.  Adjust seasonings to taste.

Line two large cookie sheets with parchment paper.

Snip the corner off a freezer bag and insert a ½-inch star tip into the corner.  Put the piping bag in a tall, wide-mouthed glass or vase and pull the sides of the bag over the glass to make it easier to put the filling in it.

Preheat the oven to 400 F.  Once they have chilled, whisk the egg white and carefully brush them with it.

Bake two trays at a time, each on a separate rack for 15 minutes.  Switch the top and bottom trays and rotate for even cooking, then cook for another 10 minutes.

Allow them to cool on the tray for 5 minutes before transferring to a serving platter.  Serve warm.