Preheat oven to 375 degrees.

Fill a large saucepan with water and add a good amount of salt and the potatoes. Bring to a boil and reduce to medium and cook until fork tender. Drain.

Lay boiled potatoes on a baking sheet and place into the oven for 10-15 minutes, or until slightly dried on the surface.

Remove the potatoes from the oven and process potatoes through a ricer or food mill. Do not use the food processor. It will make the potatoes too gummy. Allow to cool in a bowl for about 5 minutes. Add egg yolks, butter, a couple of generous pinches of salt, a generous pinch of pepper, and 3/4 cup cream. Stir with a rubber spatula to combine. Taste and make sure the potatoes have been adequately salted and add more cream if needed until the potatoes are nice and creamy.

Transfer potatoes to a large pastry bag and pipe through a large star tip in a circular/upward spiral motion onto a lightly greased baking sheet. (If making ahead - lightly place plastic wrap over potatoes and store in refrigerator.

Make an egg wash by mixing 1 egg with 1/2 cup heavy cream. Lightly brush the piped potatoes with egg wash. (This is a little easier if you chill the piped potatoes for half an hour or so.)

Bake at 375 until golden brown around the edges. Remove and serve on a platter.