how long to cook a sweet potato in the oven
1 Heat oven to 400Â° F. Pierce each sweet potato several times with the tines of a fork. 2  Place the sweet potatoes on a rimmed baking sheet lined with foil. 3  Bake until tender, about 45 minutes.4  Make a slit in the top of each sweet potato. Place the sweet potatoes on a rimmed baking sheet lined with foil. 2  Bake until tender, about 45 minutes. 3  Make a slit in the top of each sweet potato. 4  Top with 1 tablespoon of butter and season with the salt and pepper.