Wash and peel the potatoes;
Put the potatoes in a large saucepan, and cover with 1-inch cold water. Add the salt and bring to boil over high heat;
Lower heat and simmer potatoes for 20 or 30 minutes;
In the meantime, heat the milk with 1/2 tsp of salt, pepper, nutmeg, sage, and rosemary;
When the milk begins to boil, turn off the heat (the milk should not boil);
Use a fine-mesh strainer to remove all residue from the milk;
When the potatoes are soft and begin to crumble, drain them and put them through a medium sieve, a potato ricer, or a masher;
On very low heat, add butter to the potatoes. Add the milk and stir with a wooden spoon to incorporate the milk into the potatoes;
You will get a very smooth and very uniform cream;
Adjust the salt and pepper if the mashed potato is too sweet. Serve hot and enjoy!