Preheat the oven to 375. Using the tip of a knife poke holes in each sweet potato. Season liberally with olive oil and salt. Bake for one hour, flipping halfway through.
In a small bowl whisk together the miso and butter.
When the sweet potatoes come out of the oven cut them open with a sharp knife, spoon half of the butter in each potato, top with the sliced scallion and serve immediately!