Preheat oven to 400 degrees. Pierce the sweet potatoes to the middle with a thin knife a few times all over and roast for 45 minutes. Remove when tender and let cool. (Lower the oven temperature to 350.)
Cut the potato in half long ways and scoop out the tender sweet potato. Add to a food processor and also add every other ingredient. Puree until very smooth, very creamy, and lump free.
Scoop the potato mixture into a small baking dish or four individual sized ramekins. You can add more butter on top (or not if that's a little too unhealthy) though I think it's better when you do. Sprinkle a little bit of black pepper on top and bake for 25 minutes. Serve warm. (Multiply recipe as many times as needed.)