Heat oven to 400° F.
Pierce each sweet potato several times with the tines of a fork. Place the sweet potatoes on a rimmed baking sheet lined with foil. Bake until tender, about 45 minutes.
Make a slit in the top of each sweet potato. Top with 1 tablespoon of butter and season with the salt and pepper.
Variation: Baking sweet potatoes intensifies their sweetness, making them surprisingly satisfying with little, if any, embellishment. If you crave something over the top, try some maple syrup or brown sugar, a spoonful of sour cream, a pinch of ground cinnamon, some caramelized onions, a handful of pecans or walnuts, jarred applesauce or chutney, canned chipotles in adobo, crystallized ginger, or grated orange zest.