1. Add the potato pieces to a large pot and cover with cold water by about 2 inches. Stir in 3 tablespoons kosher salt.

2. Bring to a boil over medium-high heat, then lower to a gentle simmer. Cook for about 20 minutes, or until the potatoes are very tender when pierced with a fork.

3. While the potatoes cook, pour the heavy cream into a small saucepan. Add the garlic, rosemary, thyme, bay leaves, and whole peppercorns.

4. Warm the cream over medium heat, stirring now and then, until it just starts to simmer, about 6 to 8 minutes. Remove from the heat and let it steep.

5. Drain the potatoes well and return them to the warm pot.

6. Mash the hot potatoes with a potato ricer for a smoother texture, or use a potato masher for a more rustic finish.

7. Strain the warm cream mixture into the potatoes, discarding the herbs, garlic, bay leaves, and peppercorns.

8. Add the butter and mash gently until the potatoes are creamy and the butter is fully melted.

9. Season with ground black pepper and more salt to taste. Stir just until combined so the potatoes stay light and fluffy.

10. Serve right away, topped with extra black pepper and fresh chives if desired.