Place chopped sweet potatoes in a large saucepan. Cover with water; bring to a boil.
Boil 15 minutes or until tender; drain.
Combine cooked sweet potatoes and softened butter in a large mixing bowl; beat until smooth.
Add brown sugar, eggs, pumpkin pie spice, and salt and beat until blended.
Spoon into a 1.5 quart baking dish. (*You may prepare up to this point one day in advance and store, covered, in the refrigerator. Baking time will need to be increased by 15 minutes.)
Bake at 400 degrees for 25 minutes.
Combine topping ingredients in a small mixing bowl; sprinkle over casserole.