1) Peel sweet potatoes and chop into 1-inch chunks. Cook in lightly salted until the sweet potatoes are tender, about 10 minutes.
2) Drain sweet potatoes and return to the pan. Add butter, milk (or cream) and a pinch of salt and pepper. Mash until smooth. If potatoes are dry, you might need to add more milk.
You can serve these as-is while warm.
(optional) Transfer sweet potatoes to a casserole dish and top with brown sugar and marshmallows. Use a kitchen torch to lightly toast marshmallows!