Preheat oven to 350 degrees F. Butter a 1 to 1 1/2 quart baking dish and set aside.
Pierce each potato with a fork several times.
Place potatoes on a baking sheet and bake for about 1 hour, or until potatoes are very tender.
Allow potatoes to cool slightly and peel.
Blend topping ingredients together with a pastry cutter (or a fork) until crumbly and sprinkle on top.
Bake, uncovered, 25 to 30 minutes longer or until sweet potatoes are tender and topping is lightly browned.