Place a rack in the center of your oven and preheat to 425°F. For easy clean up, line a rimmed baking sheet with parchment paper or foil.
Scrub the sweet potatoes and pat it dry. Prick all over with the tines of a fork, then place on the prepared baking sheet. Bake until the sweet potatoes are very tender, the peels have lightly browned, and bits are beginning to ooze from the holes, 45 minutes to 1 hour depending on size.
Let the sweet potatoes cool. Once cool enough to handle, make use a sharp knife to cut a slit in the top. With a fork, open the split and lightly fluff the insides to make space for the toppings. Season with salt and pepper to taste. Serve warm with butter.
Notes
TO STORE: Baked sweet potatoes will keep in the refrigerator for up to 5 days. They get even sweeter as they cool!
TO REHEAT: Remove the baked sweet potato from the refrigerator and let it come to as close to room temperature as time will allow. Rewarm in a 425°F oven for 10 to 15 minutes, turning it over once halfway through. If you prefer not to use the oven, you can slice the sweet potato in half lengthwise from end-to-end, then place it cut-side down in a lightly oiled nonstick skillet heated over medium-low heat. Cover the sweet potato with a lid, reduce the heat to low, and let steam for 3 to 4 minutes, watching carefully so that the halves do not burn. The final (fastest) option is the microwave, though I find this makes the texture of the reheated sweet potato somewhat gummy.
TO FREEZE: You can wrap sweet potatoes tightly and freeze them for up to 3 months; let them thaw in the refrigerator and then reheat according to the instructions above.