Place the whole un-peeled potatoes in a large pot and fill with water until they are covered by an inch. Cover, bring to a boil, then reduce to a simmer and cook for 20 minutes. Toss the carrots and cook for another 15 minutes. Drain the vegetables in a colander. Carefully remove the skins of the potatoes. Toss everything back into the waterless pot. Go to town with a potato masher. Add the butter, mash some more. Than whisk in the heavy cream. Season with salt and pepper to taste.
