On a cutting board, peel the potatoes. Place the potatoes in a large bowl of cold water after peeling to prevent discoloration.
2. Step
Dice the potatoes into 1-inch (2-cm) cubes.
3. Step
Add the potatoes to a large pot of cold water, along with the salt. Bring to a soft boil over high heat, then reduce the heat to low and simmer for about 12 minutes, until the potatoes are fork-tender.
4. Step
Drain the potatoes in a colander, then return to the pot. Increase the heat to medium-high and stir the potatoes around for 2-3 minutes to evaporate any excess moisture.
5. Step
Transfer the potatoes to a large bowl and mash with a potato masher, potato ricer, or by pushing through a fine mesh sieve with a spatula.
6. Step
Add the melted butter and stir to incorporate, then season with salt to taste.
7. Step
In a small saucepan, combine the heavy cream, rosemary, and garlic. Bring to a simmer over low heat, let simmer for a few minutes, then remove the pot from the heat and strain through a fine mesh sieve.
8. Step
Gradually add the cream mixture to the potatoes, a little at a time, stirring until fully incorporated.
9. Step
Top with a pat of butter, freshly ground black pepper, and a sprinkle with chives, or gravy, if desired.
