Preheat the oven to 400 degrees. Line 2 baking sheets with parchment paper or a Silpat mat.

In a large pot, place the potatoes, salt, garlic, and cover with water.

Bring to a boil and cook the potatoes until they are fork-tender.

Drain the potatoes in a colander and spread them out onto paper towels to dry.  Discard the garlic cloves.

Add the potatoes back to the pot and place the pot over medium-low heat.

Add the cheese, cream, 2 tablespoons truffle butter, onion powder, garlic powder, and white pepper.

Use a potato masher to mash the potatoes and mix the ingredients together.  Continue mashing until the potatoes have a smooth texture.  Alternatively, you could use a ricer to pulverize the potatoes for an even smoother mash.

Pour in the egg yolks and quickly whip them into the potatoes.

Using a large piping bag that has been fitted with a large star tip, spoon the potatoes into the bag. Fold down the top and squeeze the potato mixture down into the tip.  If the bag is too hot to handle, wrap a dish towel around it.

Pipe about a ½ cup mound of potato onto the baking sheet, leaving at least an inch between mounds.  Pipe the mounds high as they will spread a little while baking.

Melt the remaining 4 tablespoons of truffle butter.  Use a pastry brush to gently brush the tops of the potatoes with the melted butter.

Bake in the preheated oven for 20-25 minutes or until the tops are golden.

Remove from the oven and allow to rest for 1-2 minutes.

Use a spatula to carefully lift the mounds from the baking pan and place them onto your serving platter.

Serve hot.