Peel and chop the russet potatoes into uniform chunks.
Place the potatoes in a large pot and cover with cold water.
Add a pinch of salt to the water.
Bring the water to a boil over high heat.
Reduce the heat and simmer until potatoes are tender, about 15-20 minutes.
Drain the potatoes well and return them to the pot.
Add the butter and allow it to melt into the hot potatoes.
Pour in the heavy cream gradually, while mashing the potatoes.
Mix until the potatoes are smooth and creamy, adjusting cream as needed.
Season with salt and pepper to taste and garnish with chives or parsley, if desired.