Preheat oven to 350 degrees. Using a knife, pierce sweet potatoes several times. Put on cookie sheet and bake for 1 hour, or until soft. Remove from oven and let rest for a few minutes.
Peel sweet potatoes. Put in a food processor, along with butter, maple syrup and sour cream, and mix to obtain the consistency of a purée. Put purée in a bowl, add chives, and gently mix together. Put roasted pecans on top and serve.