Better in the microwave.
Slice sweet potato in half. Place halves on microwave plate. Poke holes in each half. Put in microwave and heat for 6-8 minutes. Stop halfway through and rotate the potatoes. In a small bowl mix the butter, brown sugar, butter, nutmeg, and cinnamon. Remove the sweet potatoes when they are thoroughly heated and tender to the touch when poked by a fork.
Spoon the butter-cinnamon sauce on the hot sweet potato. Salt and season to taste.