Place the potatoes and garlic in a large pot of cold water. Bring the water to a boil and cook until the potatoes are fork tender, about 15 minutes.
3 pounds russet potatoes, 6 large garlic cloves
While the potatoes cook, place the butter and cream into a small saucepan over low heat. Cook until the butter melts and the heavy cream begins to steam. Remove from heat and set aside.
½ cup unsalted butter, ⅔ cup heavy cream
Drain the potatoes, reserving 1 cup of water. Transfer the potatoes to a large mixing bowl.
1 cup starchy potato water
Use a potato masher to mix the potatoes and cream mixture. Add the reserved water if the potatoes are too dry or not creamy enough. Taste, and season with salt and pepper. Garnish with fresh parsley.
Salt and pepper, 1 tablespoon freshly chopped parsley
See post for storage options.