Peel and cube potatoes. Place into a large pot covering with 1 inch cold water. Season with 1 tsp salt. Bring to a boil, then lower heat to medium-high cooking for 8-10 minutes or until fork tender. Drain well.
Mash potatoes using a potato masher or ricer until no lumps. Add reserved 1 tsp salt, butter, cream, cream cheese, 3 Tbsp Parmesan and garlic. Mix until fully blended. Let cool slightly, then add egg yolks. Mix thoroughly.
Preheat oven to 425°F. Line 2 baking sheets with parchment paper.
Using a piping bag or Ziploc bag fitted with a large open star tip, pipe 12 mounds, 2 inches apart.
Bake for 20-25 minutes just until tops are golden. Let stand on pan for a few minutes.
Serve immediately garnished with additional Parmesan and fresh chives.