Clean the sweet potatoes then poke them with a fork in a few places. Once the oven is hot, place them on the center rack and bake them for 45-50 minutes, or until tender when a knife is inserted into the center. Remove the cooked potatoes from the oven, slice them down the center then pinch each end of the potato towards the middle. Add butter then season with sea salt and freshly cracked pepper, to taste. Grate some fresh nutmeg over the top and serve immediately. Enjoy.