1Place sweet potatoes in 3-quart saucepan; add enough water just to cover potatoes. Cover and heat to boiling; reduce heat. Simmer covered 20 to 25 minutes or until potatoes are tender when pierced with a fork; drain. Return potatoes to saucepan. Heat potatoes over low heat about 1 minute, shaking pan often to keep potatoes from sticking and burning, to dry potatoes.
2Heat oven to 350°. Mash potatoes, 2 tablespoons butter and the salt in medium bowl with potato masher or electric mixer on low speed until no lumps remain. Spoon into ungreased 1-quart casserole. Mix remaining ingredients; sprinkle over potatoes.
3Bake uncovered about 30 minutes or until potatoes are hot and topping mixture is golden brown.