Peel the potatoes on a cutting board. To avoid discolouration, place the potatoes in a big dish of cold water after peeling.
Potatoes should be diced into 1-inch (2-cm) pieces.
Salt and the potatoes should be added to a big pot of cold water. The potatoes should be fork-tender after about 12 minutes of simmering on low heat after bringing to a soft boil over high heat.
In a container, rinse the potatoes, then add them back to the pot. To remove any extra moisture, turn the heat up to medium-high and toss the potatoes for two to three minutes.
Use a potato masher, or a spatula to push the potatoes through a fine mesh sieve to mash them in a big bowl.
After incorporating the melted butter, season with salt to taste.
Combine the heavy cream, rosemary, and garlic in a small saucepan. Over low heat, bring to a simmer, let simmer for a short while, then turn off the heat and strain through a fine mesh screen.
Small amounts of the cream mixture should be added to the potatoes at a time; stir until combined.
If preferred, add gravy, chives, a pat of butter, and freshly ground black pepper on the top.
